Managing deletions from a deduplication database

ABSTRACT

An information management system can manage the removal of data block entries in a deduplicated data store using working copies of the data block entries residing in a local data store of a secondary storage computing device. The system can use the working copies to identify data blocks for removal. Once the deduplication database is updated with the changes to the working copies (e.g., using a transaction based update scheme), the system can query the deduplication database for the database entries identified for removal. Once identified, the system can remove the database entries identified for pruning and/or the corresponding deduplication data blocks from secondary storage.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is being filed concurrently with U.S.application Ser. No. ______, entitled, MAINTAINING A DEDUPLICATIONDATABASE (Attorney Docket: COMMV.201A1), which is incorporated herein byreference in its entirety.

BACKGROUND

Businesses worldwide recognize the commercial value of their data andseek reliable, cost-effective ways to protect the information stored ontheir computer networks while minimizing impact on productivity.Protecting information is often part of a routine process that isperformed within an organization.

A company might back up critical computing systems such as databases,file servers, web servers, and so on as part of a daily, weekly, ormonthly maintenance schedule. The company may similarly protectcomputing systems used by each of its employees, such as those used byan accounting department, marketing department, engineering department,and so forth.

Given the rapidly expanding volume of data under management, companiesalso continue to seek innovative techniques for managing data growth, inaddition to protecting data. For instance, companies often implementmigration techniques for moving data to lower cost storage over time anddata reduction techniques for reducing redundant data, pruning lowerpriority data, etc.

Enterprises also increasingly view their stored data as a valuableasset. Along these lines, customers are looking for solutions that notonly protect and manage, but also leverage their data. For instance,solutions providing data analysis capabilities, improved datapresentation and access features, and the like, are in increasingdemand.

In response to these challenges, one technique developed by storagesystem providers is data deduplication. Deduplication typically involveseliminating or reducing the amount of redundant data stored andcommunicated within a storage system, improving storage utilization. Forexample, data can be divided into units of a chosen granularity (e.g.,files or sub-file data blocks). The sizes of the data blocks can be offixed or variable length. As new data enters the system, the data unitscan be checked to see if they already exist in the storage system. Ifthe data unit already exists, instead of storing and/or communicating aduplicate copy, the storage system stores and/or communicates areference to the existing data unit. Thus, deduplication can improvestorage utilization, system traffic (e.g., over a networked storagesystem), or both.

Even in those systems employing deduplication, data managementoperations, including backup and restore operations, can place heavydemands on available network bandwidth and available system resources.Such operations can also introduce significant delay, e.g., due tocommunication latency between secondary storage (e.g., non-production,backup storage) and primary storage (e.g., production storage). Inaddition, if a device or script involved in the deduplication processfails or becomes unavailable, recovering from such failures to restorethe deduplication to the pre-failure state can be quite time consuming.

SUMMARY

For example, in some cases, deduplication database pruning operations(e.g., data block deletion operations) are performed at infrequentintervals, and a lengthy log of pending pruning operations is compiledover time. At the next pruning interval, the system “plays back” the logto actually implement the pruning operations in the deduplicationdatabase. In such cases, playing back the full pruning history in theevent of a system crash can take a long time.

In accordance with certain aspects of the disclosure, solutionsdescribed herein address these and other challenges. Some of thesesolutions incorporate the use of a locally maintained data structureresiding on a secondary storage computing device or other storagecontroller computer, such as in a main memory of the secondary storagecomputing device. This local data structure can be referred to as anin-memory database (IMDB), for example. The local database can retainworking copies of deduplication database entries, where a full versionof the deduplication database exists external to the secondary storagecomputing device. For instance, the complete version of thededuplication database may be contained in one or more secondary storagedevices, and can also be referred to as an on-disk database (ODDB). Thededuplication database entries can include certain information relatedto deduplication data blocks stored in the secondary storage devices.For instance, for any given data block, the database entries can includea signature corresponding to the data block, a pointer to a copy of thedata block stored in the secondary storage devices, a count valuecorresponding to a number of references to the data block in a set ofdeduplicated files maintained in the secondary storage, and the like.The working copies in the local database can include some or all of theinformation included the corresponding database entries.

As storage operations occur in secondary storage, the system can modifythe working copy of the database entries in the local database (e.g.,residing in main memory), without initially modifying correspondingdatabase entries stored in the full version of the database. The workingcopies in the local database can be flushed from the local databasesecondary storage computing device and/or merged with the full versionof the database. For instance, the working copies may be flushed and/ormerged with the full version of the deduplication database according toa transaction-based scheme, when the local database reaches a thresholdsize or upon expiration of a threshold period of time since the lasttime the local database was flushed. The working copies can be set toread-only or otherwise set to prevent write access during thetransaction to preserve the integrity of the transaction. The thresholdsize or time period can be selected such that transactions (e.g.,additions and modifications to entries) are flushed from the localdatabase to the deduplication database with sufficient regularity tokeep the deduplication database relatively current (e.g., at no morethan 1, 2, or 5 minute intervals). This can reduce the time required forrebuilding and bringing the deduplication database back online in theevent of certain failures, such as hardware or software crashesassociated with the secondary storage computing device.

According to additional aspects, the local database can be used inconjunction with pruning certain deduplication information from theinformation management system in a manner that improves crash recovery.For instance, the system can query the merged database entries toidentify any entries indicating that a pruning event (e.g., a deletionof a data block and/or corresponding deduplication signature, etc.)should occur, such as where an entry for a particular data blockindicates that there are no longer any deduplicated files that referencean instance of that data block. If the local database is flushed andmerged with the full deduplication database at a sufficient frequency,pruning operations will be written out to and reflected in thededuplication database relatively promptly, e.g., without the need tobuild and play back a lengthy pruning log in the event of a crash. Insome embodiments, some scheduled pruning events may be missed in theevent of a crash, such as if the local database is lost prior to a mergewith the complete deduplication database. However, because of thetransaction-based scheme the database is updated relatively frequently,only a relatively small number of pruning events will be lost for anygiven crash. In such cases, this small number of pruning events can bere-issued by the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary informationmanagement system.

FIG. 1B is a detailed view of a primary storage device, a secondarystorage device, and some examples of primary data and secondary copydata.

FIG. 1C is a block diagram of an exemplary information management systemincluding a storage manager, one or more data agents, and one or moremedia agents.

FIG. 1D is a block diagram illustrating a scalable informationmanagement system.

FIG. 1E illustrates certain secondary copy operations according to anexemplary storage policy.

FIGS. 1F-1H are block diagrams illustrating suitable data structuresthat may be employed by the information management system.

FIG. 2 is a block diagram illustrative of some portions of aninformation management system configured to implement informationmanagement techniques incorporating a transaction-based deduplicationdatabase management scheme, according to an illustrative embodiment.

FIG. 3A is a block diagram illustrative of an expanded view of someportions a deduplication database according to an illustrativeembodiment.

FIG. 3B is a block diagram illustrative of an expanded view of asignature block stored in the deduplication database of FIG. 3A,according to an illustrative embodiment.

FIG. 4 is a data flow diagram illustrative of the interaction betweenvarious components of an exemplary information management system duringa merge of deduplication database information local to a secondarystorage computing device with an on-disk deduplication database,according to an illustrative embodiment.

FIG. 5 is a flow diagram illustrating some operations of a routineimplemented by an information management system for performing a mergeof deduplication database information local to a secondary storagecomputing device with an on-disk deduplication database, according to anillustrative embodiment.

FIG. 6 is data flow diagram showing the interaction between variouscomponents of an exemplary information management system during apruning operation in which one or more data blocks are deleted from adeduplicated data store, according to an illustrative embodiment.

FIG. 7 is a flow diagram illustrating some operations of a routineimplemented by an information management system for performing a pruningoperation in which one or more data blocks are deleted from adeduplicated data store, according to an illustrative embodiment.

FIG. 8 is a flow diagram illustrating some operations of a routineimplemented by an information management system for merging areconstructed local deduplication database with an on-disk deduplicationdatabase, according to an illustrative embodiment.

FIG. 9 is a flow diagram illustrating some operations of a routineimplemented by an information management system for requesting a pruneof a deduplicated data store after a failure, according to anillustrative embodiment.

DETAILED DESCRIPTION

Systems and methods are described herein for implementing atransaction-based deduplication database management scheme incorporatingthe use of deduplication information local to a secondary storagecomputing device. Some such systems and methods involve the use ofworking copies of deduplication database entries or other appropriatededuplication information maintained in main memory of the secondarystorage computing device. The working copies can be merged with adeduplication database residing in one or more secondary storage deviceson a relatively frequent basis, such as upon satisfaction of a sizethreshold of a data structure containing the working copies, or uponexpiration of a threshold period of time following the last mergeoperation. Such techniques can reduce the time required for rebuildingand bringing a deduplication data store back online in the event ofcertain failures, such as hardware or software crashes associated withthe secondary storage computing device. Examples of such systems andmethods are discussed in further detail herein, e.g., in reference toFIGS. 2-9. Moreover, it will be appreciated that such components andfunctionality may be configured for use with and/or incorporated intoinformation management systems such as those that will now be describedwith respect to FIGS. 1A-1H.

Information Management System Overview

With the increasing importance of protecting and leveraging data,organizations simply cannot afford to take the risk of losing criticaldata. Moreover, runaway data growth and other modern realities makeprotecting and managing data an increasingly difficult task. There istherefore a need for efficient, powerful, and user-friendly solutionsfor protecting and managing data.

Depending on the size of the organization, there are typically many dataproduction sources which are under the purview of tens, hundreds, oreven thousands of employees or other individuals. In the past,individual employees were sometimes responsible for managing andprotecting their data. A patchwork of hardware and software pointsolutions has been applied in other cases. These solutions were oftenprovided by different vendors and had limited or no interoperability.

Certain embodiments described herein provide systems and methods capableof addressing these and other shortcomings of prior approaches byimplementing unified, organization-wide information management. FIG. 1Ashows one such information management system 100, which generallyincludes combinations of hardware and software configured to protect andmanage data and metadata, which is generated and used by the variouscomputing devices in information management system 100. The organizationthat employs the information management system 100 may be a corporationor other business entity, non-profit organization, educationalinstitution, household, governmental agency, or the like.

Generally, the systems and associated components described herein may becompatible with and/or provide some or all of the functionality of thesystems and corresponding components described in one or more of thefollowing U.S. patents and patent application publications assigned toCommVault Systems, Inc., each of which is hereby incorporated in itsentirety by reference herein:

-   -   U.S. Pat. No. 8,285,681, entitled “Data Object Store and Server        for a Cloud Storage Environment, Including Data Deduplication        and Data Management Across Multiple Cloud Storage Sites”;    -   U.S. Pat. No. 8,307,177, entitled “Systems And Methods For        Management Of Virtualization Data”;    -   U.S. Pat. No. 7,035,880, entitled “Modular Backup and Retrieval        System Used in Conjunction With a Storage Area Network”;    -   U.S. Pat. No. 7,343,453, entitled “Hierarchical Systems and        Methods for Providing a Unified View of Storage Information”;    -   U.S. Pat. No. 7,395,282, entitled “Hierarchical Backup and        Retrieval System”;    -   U.S. Pat. No. 7,246,207, entitled “System and Method for        Dynamically Performing Storage Operations in a Computer        Network”;    -   U.S. Pat. No. 7,747,579, entitled “Metabase for Facilitating        Data Classification”;    -   U.S. Pat. No. 8,229,954, entitled “Managing Copies of Data”;    -   U.S. Pat. No. 7,617,262, entitled “System and Methods for        Monitoring Application Data in a Data Replication System”;    -   U.S. Pat. No. 7,529,782, entitled “System and Methods for        Performing a Snapshot and for Restoring Data”;    -   U.S. Pat. No. 8,230,195, entitled “System And Method For        Performing Auxiliary Storage Operations”;    -   U.S. Pat. No. 7,315,923, entitled “System And Method For        Combining Data Streams In Pipelined Storage Operations In A        Storage Network”;    -   U.S. Pat. No. 8,364,652, entitled “Content-Aligned, Block-Based        Deduplication”;    -   U.S. Pat. Pub. No. 2006/0224846, entitled “System and Method to        Support Single Instance Storage Operations”;    -   U.S. Pat. No. 8,578,120, entitled “Block-Level Single        Instancing”;    -   U.S. Pat. Pub. No. 2009/0319534, entitled “Application-Aware and        Remote Single Instance Data Management”;    -   U.S. Pat. Pub. No. 2012/0150826, entitled “Distributed        Deduplicated Storage System”;    -   U.S. Pat. Pub. No. 2012/0150818, entitled “Client-Side        Repository in a Networked Deduplicated Storage System”;    -   U.S. Pat. No. 8,170,995, entitled “Method and System for Offline        Indexing of Content and Classifying Stored Data”;    -   U.S. Pat. No. 7,107,298, entitled “System And Method For        Archiving Objects In An Information Store”;    -   U.S. Pat. No. 8,230,195, entitled “System And Method For        Performing Auxiliary Storage Operations”;    -   U.S. Pat. No. 8,229,954, entitled “Managing Copies Of Data”; and    -   U.S. Pat. No. 8,156,086, entitled “Systems And Methods For        Stored Data Verification”.

The information management system 100 can include a variety of differentcomputing devices. For instance, as will be described in greater detailherein, the information management system 100 can include one or moreclient computing devices 102 and secondary storage computing devices106.

Computing devices can include, without limitation, one or more:workstations, personal computers, desktop computers, or other types ofgenerally fixed computing systems such as mainframe computers andminicomputers. Other computing devices can include mobile or portablecomputing devices, such as one or more laptops, tablet computers,personal data assistants, mobile phones (such as smartphones), and othermobile or portable computing devices such as embedded computers, set topboxes, vehicle-mounted devices, wearable computers, etc. Computingdevices can include servers, such as mail servers, file servers,database servers, and web servers.

In some cases, a computing device includes virtualized and/or cloudcomputing resources. For instance, one or more virtual machines may beprovided to the organization by a third-party cloud service vendor. Or,in some embodiments, computing devices can include one or more virtualmachine(s) running on a physical host computing device (or “hostmachine”) operated by the organization. As one example, the organizationmay use one virtual machine as a database server and another virtualmachine as a mail server, both virtual machines operating on the samehost machine.

A virtual machine includes an operating system and associated virtualresources, and is hosted simultaneously with another operating system ona physical host computer (or host machine). A hypervisor (typicallysoftware, and also known in the art as a virtual machine monitor or avirtual machine manager or “VMM”) sits between the virtual machine andthe hardware of the physical host machine. One example of hypervisor asvirtualization software is ESX Server, by VMware, Inc. of Palo Alto,Calif.; other examples include Microsoft Virtual Server and MicrosoftWindows Server Hyper-V, both by Microsoft Corporation of Redmond, Wash.,and Sun xVM by Oracle America Inc. of Santa Clara, Calif. In someembodiments, the hypervisor may be firmware or hardware or a combinationof software and/or firmware and/or hardware.

The hypervisor provides to each virtual operating system virtualresources, such as a virtual processor, virtual memory, a virtualnetwork device, and a virtual disk. Each virtual machine has one or morevirtual disks. The hypervisor typically stores the data of virtual disksin files on the file system of the physical host machine, called virtualmachine disk files (in the case of VMware virtual servers) or virtualhard disk image files (in the case of Microsoft virtual servers). Forexample, VMware's ESX Server provides the Virtual Machine File System(VMFS) for the storage of virtual machine disk files. A virtual machinereads data from and writes data to its virtual disk much the same waythat an actual physical machine reads data from and writes data to anactual disk.

Examples of techniques for implementing information managementtechniques in a cloud computing environment are described in U.S. Pat.No. 8,285,681, which is incorporated by reference herein. Examples oftechniques for implementing information management techniques in avirtualized computing environment are described in U.S. Pat. No.8,307,177, also incorporated by reference herein.

The information management system 100 can also include a variety ofstorage devices, including primary storage devices 104 and secondarystorage devices 108, for example. Storage devices can generally be ofany suitable type including, without limitation, disk drives, hard-diskarrays, semiconductor memory (e.g., solid state storage devices),network attached storage (NAS) devices, tape libraries or othermagnetic, non-tape storage devices, optical media storage devices,DNA/RNA-based memory technology, combinations of the same, and the like.In some embodiments, storage devices can form part of a distributed filesystem. In some cases, storage devices are provided in a cloud (e.g., aprivate cloud or one operated by a third-party vendor). A storage devicein some cases comprises a disk array or portion thereof.

The illustrated information management system 100 includes one or moreclient computing device 102 having at least one application 110executing thereon, and one or more primary storage devices 104 storingprimary data 112. The client computing device(s) 102 and the primarystorage devices 104 may generally be referred to in some cases as aprimary storage subsystem 117. A computing device in an informationmanagement system 100 that has a data agent 142 installed and operatingon it is generally referred to as a client computing device 102 (or, inthe context of a component of the information management system 100simply as a “client”).

Depending on the context, the term “information management system” canrefer to generally all of the illustrated hardware and softwarecomponents. Or, in other instances, the term may refer to only a subsetof the illustrated components.

For instance, in some cases, the information management system 100generally refers to a combination of specialized components used toprotect, move, manage, manipulate, analyze, and/or process data andmetadata generated by the client computing devices 102. However, theinformation management system 100 in some cases does not include theunderlying components that generate and/or store the primary data 112,such as the client computing devices 102 themselves, the applications110 and operating system operating on the client computing devices 102,and the primary storage devices 104. As an example, “informationmanagement system” may sometimes refer to one or more of the followingcomponents and corresponding data structures: storage managers, dataagents, and media agents. These components will be described in furtherdetail below.

Client Computing Devices

There are typically a variety of sources in an organization that producedata to be protected and managed. As just one illustrative example, in acorporate environment such data sources can be employee workstations andcompany servers such as a mail server, a web server, a database server,a transaction server, or the like. In the information management system100, the data generation sources include the one or more clientcomputing devices 102.

The client computing devices 102 may include any of the types ofcomputing devices described above, without limitation, and in some casesthe client computing devices 102 are associated with one or more usersand/or corresponding user accounts, of employees or other individuals.

The information management system 100 generally addresses and handlesthe data management and protection needs for the data generated by theclient computing devices 102. However, the use of this term does notimply that the client computing devices 102 cannot be “servers” in otherrespects. For instance, a particular client computing device 102 may actas a server with respect to other devices, such as other clientcomputing devices 102. As just a few examples, the client computingdevices 102 can include mail servers, file servers, database servers,and web servers.

Each client computing device 102 may have one or more applications 110(e.g., software applications) executing thereon which generate andmanipulate the data that is to be protected from loss and managed. Theapplications 110 generally facilitate the operations of an organization(or multiple affiliated organizations), and can include, withoutlimitation, mail server applications (e.g., Microsoft Exchange Server),file server applications, mail client applications (e.g., MicrosoftExchange Client), database applications (e.g., SQL, Oracle, SAP, LotusNotes Database), word processing applications (e.g., Microsoft Word),spreadsheet applications, financial applications, presentationapplications, graphics and/or video applications, browser applications,mobile applications, entertainment applications, and so on.

The client computing devices 102 can have at least one operating system(e.g., Microsoft Windows, Mac OS X, iOS, IBM z/OS, Linux, otherUnix-based operating systems, etc.) installed thereon, which may supportor host one or more file systems and other applications 110.

The client computing devices 102 and other components in informationmanagement system 100 can be connected to one another via one or morecommunication pathways 114. For example, a first communication pathway114 may connect (or communicatively couple) client computing device 102and secondary storage computing device 106; a second communicationpathway 114 may connect storage manager 140 and client computing device102; and a third communication pathway 114 may connect storage manager140 and secondary storage computing device 106, etc. (see, e.g., FIG. 1Aand FIG. 1C). The communication pathways 114 can include one or morenetworks or other connection types including one or more of thefollowing, without limitation: the Internet, a wide area network (WAN),a local area network (LAN), a Storage Area Network (SAN), a FibreChannel connection, a Small Computer System Interface (SCSI) connection,a virtual private network (VPN), a token ring or TCP/IP based network,an intranet network, a point-to-point link, a cellular network, awireless data transmission system, a two-way cable system, aninteractive kiosk network, a satellite network, a broadband network, abaseband network, a neural network, a mesh network, an ad hoc network,other appropriate wired, wireless, or partially wired/wireless computeror telecommunications networks, combinations of the same or the like.The communication pathways 114 in some cases may also includeapplication programming interfaces (APIs) including, e.g., cloud serviceprovider APIs, virtual machine management APIs, and hosted serviceprovider APIs. The underlying infrastructure of communication paths 114may be wired and/or wireless, analog and/or digital, or any combinationthereof; and the facilities used may be private, public, third-partyprovided, or any combination thereof, without limitation.

Primary Data and Exemplary Primary Storage Devices

Primary data 112 according to some embodiments is production data orother “live” data generated by the operating system and/or applications110 operating on a client computing device 102. The primary data 112 isgenerally stored on the primary storage device(s) 104 and is organizedvia a file system supported by the client computing device 102. Forinstance, the client computing device(s) 102 and correspondingapplications 110 may create, access, modify, write, delete, andotherwise use primary data 112. In some cases, some or all of theprimary data 112 can be stored in cloud storage resources (e.g., primarystorage device 104 may be a cloud-based resource).

Primary data 112 is generally in the native format of the sourceapplication 110. According to certain aspects, primary data 112 is aninitial or first (e.g., created before any other copies or before atleast one other copy) stored copy of data generated by the sourceapplication 110. Primary data 112 in some cases is created substantiallydirectly from data generated by the corresponding source applications110.

The primary storage devices 104 storing the primary data 112 may berelatively fast and/or expensive technology (e.g., a disk drive, ahard-disk array, solid state memory, etc.). In addition, primary data112 may be highly changeable and/or may be intended for relatively shortterm retention (e.g., hours, days, or weeks).

According to some embodiments, the client computing device 102 canaccess primary data 112 from the primary storage device 104 by makingconventional file system calls via the operating system. Primary data112 may include structured data (e.g., database files), unstructureddata (e.g., documents), and/or semi-structured data. Some specificexamples are described below with respect to FIG. 1B.

It can be useful in performing certain tasks to organize the primarydata 112 into units of different granularities. In general, primary data112 can include files, directories, file system volumes, data blocks,extents, or any other hierarchies or organizations of data objects. Asused herein, a “data object” can refer to both (1) any file that iscurrently addressable by a file system or that was previouslyaddressable by the file system (e.g., an archive file) and (2) a subsetof such a file (e.g., a data block).

As will be described in further detail, it can also be useful inperforming certain functions of the information management system 100 toaccess and modify metadata within the primary data 112. Metadatagenerally includes information about data objects or characteristicsassociated with the data objects. For simplicity herein, it is to beunderstood that, unless expressly stated otherwise, any reference toprimary data 112 generally also includes its associated metadata, butreferences to the metadata do not include the primary data.

Metadata can include, without limitation, one or more of the following:the data owner (e.g., the client or user that generates the data), thelast modified time (e.g., the time of the most recent modification ofthe data object), a data object name (e.g., a file name), a data objectsize (e.g., a number of bytes of data), information about the content(e.g., an indication as to the existence of a particular search term),user-supplied tags, to/from information for email (e.g., an emailsender, recipient, etc.), creation date, file type (e.g., format orapplication type), last accessed time, application type (e.g., type ofapplication that generated the data object), location/network (e.g., acurrent, past or future location of the data object and network pathwaysto/from the data object), geographic location (e.g., GPS coordinates),frequency of change (e.g., a period in which the data object ismodified), business unit (e.g., a group or department that generates,manages or is otherwise associated with the data object), aginginformation (e.g., a schedule, such as a time period, in which the dataobject is migrated to secondary or long term storage), boot sectors,partition layouts, file location within a file folder directorystructure, user permissions, owners, groups, access control lists[ACLs]), system metadata (e.g., registry information), combinations ofthe same or other similar information related to the data object.

In addition to metadata generated by or related to file systems andoperating systems, some of the applications 110 and/or other componentsof the information management system 100 maintain indices of metadatafor data objects, e.g., metadata associated with individual emailmessages. Thus, each data object may be associated with correspondingmetadata. The use of metadata to perform classification and otherfunctions is described in greater detail below.

Each of the client computing devices 102 are generally associated withand/or in communication with one or more of the primary storage devices104 storing corresponding primary data 112. A client computing device102 may be considered to be “associated with” or “in communication with”a primary storage device 104 if it is capable of one or more of: routingand/or storing data (e.g., primary data 112) to the particular primarystorage device 104, coordinating the routing and/or storing of data tothe particular primary storage device 104, retrieving data from theparticular primary storage device 104, coordinating the retrieval ofdata from the particular primary storage device 104, and modifyingand/or deleting data retrieved from the particular primary storagedevice 104.

The primary storage devices 104 can include any of the different typesof storage devices described above, or some other kind of suitablestorage device. The primary storage devices 104 may have relatively fastI/O times and/or are relatively expensive in comparison to the secondarystorage devices 108. For example, the information management system 100may generally regularly access data and metadata stored on primarystorage devices 104, whereas data and metadata stored on the secondarystorage devices 108 is accessed relatively less frequently.

Primary storage device 104 may be dedicated or shared. In some cases,each primary storage device 104 is dedicated to an associated clientcomputing device 102. For instance, a primary storage device 104 in oneembodiment is a local disk drive of a corresponding client computingdevice 102. In other cases, one or more primary storage devices 104 canbe shared by multiple client computing devices 102, e.g., via a networksuch as in a cloud storage implementation. As one example, a primarystorage device 104 can be a disk array shared by a group of clientcomputing devices 102, such as one of the following types of diskarrays: EMC Clariion, EMC Symmetrix, EMC Celerra, Dell EqualLogic, IBMXIV, NetApp FAS, HP EVA, and HP 3PAR.

The information management system 100 may also include hosted services(not shown), which may be hosted in some cases by an entity other thanthe organization that employs the other components of the informationmanagement system 100. For instance, the hosted services may be providedby various online service providers to the organization. Such serviceproviders can provide services including social networking services,hosted email services, or hosted productivity applications or otherhosted applications). Hosted services may include software-as-a-service(SaaS), platform-as-a-service (PaaS), application service providers(ASPs), cloud services, or other mechanisms for delivering functionalityvia a network. As it provides services to users, each hosted service maygenerate additional data and metadata under management of theinformation management system 100, e.g., as primary data 112. In somecases, the hosted services may be accessed using one of the applications110. As an example, a hosted mail service may be accessed via browserrunning on a client computing device 102. The hosted services may beimplemented in a variety of computing environments. In some cases, theyare implemented in an environment having a similar arrangement to theinformation management system 100, where various physical and logicalcomponents are distributed over a network.

Secondary Copies and Exemplary Secondary Storage Devices

The primary data 112 stored on the primary storage devices 104 may becompromised in some cases, such as when an employee deliberately oraccidentally deletes or overwrites primary data 112 during their normalcourse of work. Or the primary storage devices 104 can be damaged, lost,or otherwise corrupted. For recovery and/or regulatory compliancepurposes, it is therefore useful to generate copies of the primary data112. Accordingly, the information management system 100 includes one ormore secondary storage computing devices 106 and one or more secondarystorage devices 108 configured to create and store one or more secondarycopies 116 of the primary data 112 and associated metadata. Thesecondary storage computing devices 106 and the secondary storagedevices 108 may sometimes be referred to as a secondary storagesubsystem 118.

Creation of secondary copies 116 can help in search and analysis effortsand meet other information management goals, such as: restoring dataand/or metadata if an original version (e.g., of primary data 112) islost (e.g., by deletion, corruption, or disaster); allowingpoint-in-time recovery; complying with regulatory data retention andelectronic discovery (e-discovery) requirements; reducing utilizedstorage capacity; facilitating organization and search of data;improving user access to data files across multiple computing devicesand/or hosted services; and implementing data retention policies.

The client computing devices 102 access or receive primary data 112 andcommunicate the data, e.g., over one or more communication pathways 114,for storage in the secondary storage device(s) 108.

A secondary copy 116 can comprise a separate stored copy of applicationdata that is derived from one or more earlier-created, stored copies(e.g., derived from primary data 112 or another secondary copy 116).Secondary copies 116 can include point-in-time data, and may be intendedfor relatively long-term retention (e.g., weeks, months or years),before some or all of the data is moved to other storage or isdiscarded.

In some cases, a secondary copy 116 is a copy of application datacreated and stored subsequent to at least one other stored instance(e.g., subsequent to corresponding primary data 112 or to anothersecondary copy 116), in a different storage device than at least oneprevious stored copy, and/or remotely from at least one previous storedcopy. In some other cases, secondary copies can be stored in the samestorage device as primary data 112 and/or other previously storedcopies. For example, in one embodiment a disk array capable ofperforming hardware snapshots stores primary data 112 and creates andstores hardware snapshots of the primary data 112 as secondary copies116. Secondary copies 116 may be stored in relatively slow and/or lowcost storage (e.g., magnetic tape). A secondary copy 116 may be storedin a backup or archive format, or in some other format different thanthe native source application format or other primary data format.

In some cases, secondary copies 116 are indexed so users can browse andrestore at another point in time. After creation of a secondary copy 116representative of certain primary data 112, a pointer or other locationindicia (e.g., a stub) may be placed in primary data 112, or beotherwise associated with primary data 112 to indicate the currentlocation on the secondary storage device(s) 108 of secondary copy 116.

Since an instance of a data object or metadata in primary data 112 maychange over time as it is modified by an application 110 (or hostedservice or the operating system), the information management system 100may create and manage multiple secondary copies 116 of a particular dataobject or metadata, each representing the state of the data object inprimary data 112 at a particular point in time. Moreover, since aninstance of a data object in primary data 112 may eventually be deletedfrom the primary storage device 104 and the file system, the informationmanagement system 100 may continue to manage point-in-timerepresentations of that data object, even though the instance in primarydata 112 no longer exists.

For virtualized computing devices the operating system and otherapplications 110 of the client computing device(s) 102 may executewithin or under the management of virtualization software (e.g., a VMM),and the primary storage device(s) 104 may comprise a virtual diskcreated on a physical storage device. The information management system100 may create secondary copies 116 of the files or other data objectsin a virtual disk file and/or secondary copies 116 of the entire virtualdisk file itself (e.g., of an entire.vmdk file).

Secondary copies 116 may be distinguished from corresponding primarydata 112 in a variety of ways, some of which will now be described.First, as discussed, secondary copies 116 can be stored in a differentformat (e.g., backup, archive, or other non-native format) than primarydata 112. For this or other reasons, secondary copies 116 may not bedirectly useable by the applications 110 of the client computing device102, e.g., via standard system calls or otherwise without modification,processing, or other intervention by the information management system100.

Secondary copies 116 are also in some embodiments stored on a secondarystorage device 108 that is inaccessible to the applications 110 runningon the client computing devices 102 (and/or hosted services). Somesecondary copies 116 may be “offline copies,” in that they are notreadily available (e.g., not mounted to tape or disk). Offline copiescan include copies of data that the information management system 100can access without human intervention (e.g., tapes within an automatedtape library, but not yet mounted in a drive), and copies that theinformation management system 100 can access only with at least somehuman intervention (e.g., tapes located at an offsite storage site).

The Use of Intermediate Devices for Creating Secondary Copies

Creating secondary copies can be a challenging task. For instance, therecan be hundreds or thousands of client computing devices 102 continuallygenerating large volumes of primary data 112 to be protected. Also,there can be significant overhead involved in the creation of secondarycopies 116. Moreover, secondary storage devices 108 may be specialpurpose components, and interacting with them can require specializedintelligence.

In some cases, the client computing devices 102 interact directly withthe secondary storage device 108 to create the secondary copies 116.However, in view of the factors described above, this approach cannegatively impact the ability of the client computing devices 102 toserve the applications 110 and produce primary data 112. Further, theclient computing devices 102 may not be optimized for interaction withthe secondary storage devices 108.

Thus, in some embodiments, the information management system 100includes one or more software and/or hardware components which generallyact as intermediaries between the client computing devices 102 and thesecondary storage devices 108. In addition to off-loading certainresponsibilities from the client computing devices 102, theseintermediate components can provide other benefits. For instance, asdiscussed further below with respect to FIG. 1D, distributing some ofthe work involved in creating secondary copies 116 can enhancescalability.

The intermediate components can include one or more secondary storagecomputing devices 106 as shown in FIG. 1A and/or one or more mediaagents, which can be software modules operating on correspondingsecondary storage computing devices 106 (or other appropriate computingdevices). Media agents are discussed below (e.g., with respect to FIGS.1C-1E).

The secondary storage computing device(s) 106 can comprise any of thecomputing devices described above, without limitation. In some cases,the secondary storage computing device(s) 106 include specializedhardware and/or software componentry for interacting with the secondarystorage devices 108.

To create a secondary copy 116 involving the copying of data from theprimary storage subsystem 117 to the secondary storage subsystem 118,the client computing device 102 in some embodiments communicates theprimary data 112 to be copied (or a processed version thereof) to thedesignated secondary storage computing device 106, via the communicationpathway 114. The secondary storage computing device 106 in turn conveysthe received data (or a processed version thereof) to the secondarystorage device 108. In some such configurations, the communicationpathway 114 between the client computing device 102 and the secondarystorage computing device 106 comprises a portion of a LAN, WAN or SAN.In other cases, at least some client computing devices 102 communicatedirectly with the secondary storage devices 108 (e.g., via Fibre Channelor SCSI connections). In some other cases, one or more secondary copies116 are created from existing secondary copies, such as in the case ofan auxiliary copy operation, described in greater detail below.

Exemplary Primary Data and an Exemplary Secondary Copy

FIG. 1B is a detailed view showing some specific examples of primarydata stored on the primary storage device(s) 104 and secondary copy datastored on the secondary storage device(s) 108, with other components inthe system removed for the purposes of illustration. Stored on theprimary storage device(s) 104 are primary data objects including wordprocessing documents 119A-B, spreadsheets 120, presentation documents122, video files 124, image files 126, email mailboxes 128 (andcorresponding email messages 129A-C), html/xml or other types of markuplanguage files 130, databases 132 and corresponding tables or other datastructures 133A-133C).

Some or all primary data objects are associated with correspondingmetadata (e.g., “Meta1-11”), which may include file system metadataand/or application specific metadata. Stored on the secondary storagedevice(s) 108 are secondary copy data objects 134A-C which may includecopies of or otherwise represent corresponding primary data objects andmetadata.

As shown, the secondary copy data objects 134A-C can individuallyrepresent more than one primary data object. For example, secondary copydata object 134A represents three separate primary data objects 133C,122, and 129C (represented as 133C′, 122′, and 129C′, respectively, andaccompanied by the corresponding metadata Meta11, Meta3, and Meta8,respectively). Moreover, as indicated by the prime mark (′), a secondarycopy object may store a representation of a primary data object and/ormetadata differently than the original format, e.g., in a compressed,encrypted, deduplicated, or other modified format. Likewise, secondarydata object 134B represents primary data objects 120, 133B, and 119A as120′, 133B′, and 119A′, respectively and accompanied by correspondingmetadata Meta2, Meta10, and Meta1, respectively. Also, secondary dataobject 134C represents primary data objects 133A, 119B, and 129A as133A′, 119B′, and 129A′, respectively, accompanied by correspondingmetadata Meta9, Meta5, and Meta6, respectively.

Exemplary Information Management System Architecture

The information management system 100 can incorporate a variety ofdifferent hardware and software components, which can in turn beorganized with respect to one another in many different configurations,depending on the embodiment. There are critical design choices involvedin specifying the functional responsibilities of the components and therole of each component in the information management system 100. Forinstance, as will be discussed, such design choices can impactperformance as well as the adaptability of the information managementsystem 100 to data growth or other changing circumstances.

FIG. 1C shows an information management system 100 designed according tothese considerations and which includes: storage manager 140, acentralized storage and/or information manager that is configured toperform certain control functions, one or more data agents 142 executingon the client computing device(s) 102 configured to process primary data112, and one or more media agents 144 executing on the one or moresecondary storage computing devices 106 for performing tasks involvingthe secondary storage devices 108. While distributing functionalityamongst multiple computing devices can have certain advantages, in othercontexts it can be beneficial to consolidate functionality on the samecomputing device. As such, in various other embodiments, one or more ofthe components shown in FIG. 1C as being implemented on separatecomputing devices are implemented on the same computing device. In oneconfiguration, a storage manager 140, one or more data agents 142, andone or more media agents 144 are all implemented on the same computingdevice. In another embodiment, one or more data agents 142 and one ormore media agents 144 are implemented on the same computing device,while the storage manager 140 is implemented on a separate computingdevice, etc. without limitation.

Storage Manager

As noted, the number of components in the information management system100 and the amount of data under management can be quite large. Managingthe components and data is therefore a significant task, and a task thatcan grow in an often unpredictable fashion as the quantity of componentsand data scale to meet the needs of the organization. For these andother reasons, according to certain embodiments, responsibility forcontrolling the information management system 100, or at least asignificant portion of that responsibility, is allocated to the storagemanager 140. By distributing control functionality in this manner, thestorage manager 140 can be adapted independently according to changingcircumstances. Moreover, a computing device for hosting the storagemanager 140 can be selected to best suit the functions of the storagemanager 140. These and other advantages are described in further detailbelow with respect to FIG. 1D.

The storage manager 140 may be a software module or other application,which, in some embodiments operates in conjunction with one or moreassociated data structures, e.g., a dedicated database (e.g., managementdatabase 146). In some embodiments, storage manager 140 is a computingdevice comprising circuitry for executing computer instructions andperforms the functions described herein. The storage manager generallyinitiates, performs, coordinates and/or controls storage and otherinformation management operations performed by the informationmanagement system 100, e.g., to protect and control the primary data 112and secondary copies 116 of data and metadata. In general, storagemanager 100 may be said to manage information management system 100,which includes managing the constituent components, e.g., data agentsand media agents, etc.

As shown by the dashed arrowed lines 114 in FIG. 1C, the storage manager140 may communicate with and/or control some or all elements of theinformation management system 100, such as the data agents 142 and mediaagents 144. Thus, in certain embodiments, control information originatesfrom the storage manager 140 and status reporting is transmitted tostorage manager 140 by the various managed components, whereas payloaddata and payload metadata is generally communicated between the dataagents 142 and the media agents 144 (or otherwise between the clientcomputing device(s) 102 and the secondary storage computing device(s)106), e.g., at the direction of and under the management of the storagemanager 140. Control information can generally include parameters andinstructions for carrying out information management operations, suchas, without limitation, instructions to perform a task associated withan operation, timing information specifying when to initiate a taskassociated with an operation, data path information specifying whatcomponents to communicate with or access in carrying out an operation,and the like. Payload data, on the other hand, can include the actualdata involved in the storage operation, such as content data written toa secondary storage device 108 in a secondary copy operation. Payloadmetadata can include any of the types of metadata described herein, andmay be written to a storage device along with the payload content data(e.g., in the form of a header).

In other embodiments, some information management operations arecontrolled by other components in the information management system 100(e.g., the media agent(s) 144 or data agent(s) 142), instead of or incombination with the storage manager 140.

According to certain embodiments, the storage manager 140 provides oneor more of the following functions:

-   -   initiating execution of secondary copy operations;    -   managing secondary storage devices 108 and inventory/capacity of        the same;    -   reporting, searching, and/or classification of data in the        information management system 100;    -   allocating secondary storage devices 108 for secondary storage        operations;    -   monitoring completion of and providing status reporting related        to secondary storage operations;    -   tracking age information relating to secondary copies 116,        secondary storage devices 108, and comparing the age information        against retention guidelines;    -   tracking movement of data within the information management        system 100;    -   tracking logical associations between components in the        information management system 100;    -   protecting metadata associated with the information management        system 100; and    -   implementing operations management functionality.

The storage manager 140 may maintain a database 146 (or “storage managerdatabase 146” or “management database 146”) of management-related dataand information management policies 148. The database 146 may include amanagement index 150 (or “index 150”) or other data structure thatstores logical associations between components of the system, userpreferences and/or profiles (e.g., preferences regarding encryption,compression, or deduplication of primary or secondary copy data,preferences regarding the scheduling, type, or other aspects of primaryor secondary copy or other operations, mappings of particularinformation management users or user accounts to certain computingdevices or other components, etc.), management tasks, mediacontainerization, or other useful data. For example, the storage manager140 may use the index 150 to track logical associations between mediaagents 144 and secondary storage devices 108 and/or movement of datafrom primary storage devices 104 to secondary storage devices 108. Forinstance, the index 150 may store data associating a client computingdevice 102 with a particular media agent 144 and/or secondary storagedevice 108, as specified in an information management policy 148 (e.g.,a storage policy, which is defined in more detail below).

Administrators and other people may be able to configure and initiatecertain information management operations on an individual basis. Butwhile this may be acceptable for some recovery operations or otherrelatively less frequent tasks, it is often not workable forimplementing on-going organization-wide data protection and management.Thus, the information management system 100 may utilize informationmanagement policies 148 for specifying and executing informationmanagement operations (e.g., on an automated basis). Generally, aninformation management policy 148 can include a data structure or otherinformation source that specifies a set of parameters (e.g., criteriaand rules) associated with storage or other information managementoperations.

The storage manager database 146 may maintain the information managementpolicies 148 and associated data, although the information managementpolicies 148 can be stored in any appropriate location. For instance, aninformation management policy 148 such as a storage policy may be storedas metadata in a media agent database 152 or in a secondary storagedevice 108 (e.g., as an archive copy) for use in restore operations orother information management operations, depending on the embodiment.Information management policies 148 are described further below.

According to certain embodiments, the storage manager database 146comprises a relational database (e.g., an SQL database) for trackingmetadata, such as metadata associated with secondary copy operations(e.g., what client computing devices 102 and corresponding data wereprotected). This and other metadata may additionally be stored in otherlocations, such as at the secondary storage computing devices 106 or onthe secondary storage devices 108, allowing data recovery without theuse of the storage manager 140 in some cases.

As shown, the storage manager 140 may include a jobs agent 156, a userinterface 158, and a management agent 154, all of which may beimplemented as interconnected software modules or application programs.

The jobs agent 156 in some embodiments initiates, controls, and/ormonitors the status of some or all storage or other informationmanagement operations previously performed, currently being performed,or scheduled to be performed by the information management system 100.For instance, the jobs agent 156 may access information managementpolicies 148 to determine when and how to initiate and control secondarycopy and other information management operations, as will be discussedfurther.

The user interface 158 may include information processing and displaysoftware, such as a graphical user interface (“GUI”), an applicationprogram interface (“API”), or other interactive interface(s) throughwhich users and system processes can retrieve information about thestatus of information management operations (e.g., storage operations)or issue instructions to the information management system 100 and itsconstituent components. Via the user interface 158, users may optionallyissue instructions to the components in the information managementsystem 100 regarding performance of storage and recovery operations. Forexample, a user may modify a schedule concerning the number of pendingsecondary copy operations. As another example, a user may employ the GUIto view the status of pending storage operations or to monitor thestatus of certain components in the information management system 100(e.g., the amount of capacity left in a storage device).

An “information management cell” (or “storage operation cell” or “cell”)may generally include a logical and/or physical grouping of acombination of hardware and software components associated withperforming information management operations on electronic data,typically one storage manager 140 and at least one client computingdevice 102 (comprising data agent(s) 142) and at least one media agent144. For instance, the components shown in FIG. 1C may together form aninformation management cell. Multiple cells may be organizedhierarchically. With this configuration, cells may inherit propertiesfrom hierarchically superior cells or be controlled by other cells inthe hierarchy (automatically or otherwise). Alternatively, in someembodiments, cells may inherit or otherwise be associated withinformation management policies, preferences, information managementmetrics, or other properties or characteristics according to theirrelative position in a hierarchy of cells. Cells may also be delineatedand/or organized hierarchically according to function, geography,architectural considerations, or other factors useful or desirable inperforming information management operations. A first cell may representa geographic segment of an enterprise, such as a Chicago office, and asecond cell may represent a different geographic segment, such as a NewYork office. Other cells may represent departments within a particularoffice. Where delineated by function, a first cell may perform one ormore first types of information management operations (e.g., one or morefirst types of secondary or other copies), and a second cell may performone or more second types of information management operations (e.g., oneor more second types of secondary or other copies).

The storage manager 140 may also track information that permits it toselect, designate, or otherwise identify content indices, deduplicationdatabases, or similar databases or resources or data sets within itsinformation management cell (or another cell) to be searched in responseto certain queries. Such queries may be entered by the user viainteraction with the user interface 158. In general, the managementagent 154 allows multiple information management cells to communicatewith one another. For example, the information management system 100 insome cases may be one information management cell of a network ofmultiple cells adjacent to one another or otherwise logically related ina WAN or LAN. With this arrangement, the cells may be connected to oneanother through respective management agents 154.

For instance, the management agent 154 can provide the storage manager140 with the ability to communicate with other components within theinformation management system 100 (and/or other cells within a largerinformation management system) via network protocols and applicationprogramming interfaces (“APIs”) including, e.g., HTTP, HTTPS, FTP, REST,virtualization software APIs, cloud service provider APIs, and hostedservice provider APIs. Inter-cell communication and hierarchy isdescribed in greater detail in e.g., U.S. Pat. Nos. 7,747,579 and7,343,453, which are incorporated by reference herein.

Data Agents

As discussed, a variety of different types of applications 110 canoperate on a given client computing device 102, including operatingsystems, database applications, e-mail applications, and virtualmachines, just to name a few. And, as part of the process of creatingand restoring secondary copies 116, the client computing devices 102 maybe tasked with processing and preparing the primary data 112 from thesevarious different applications 110. Moreover, the nature of theprocessing/preparation can differ across clients and application types,e.g., due to inherent structural and formatting differences amongapplications 110.

The one or more data agent(s) 142 are therefore advantageouslyconfigured in some embodiments to assist in the performance ofinformation management operations based on the type of data that isbeing protected, at a client-specific and/or application-specific level.

The data agent 142 may be a software module or component that isgenerally responsible for managing, initiating, or otherwise assistingin the performance of information management operations in informationmanagement system 100, generally as directed by storage manager 140. Forinstance, the data agent 142 may take part in performing data storageoperations such as the copying, archiving, migrating, and/or replicatingof primary data 112 stored in the primary storage device(s) 104. Thedata agent 142 may receive control information from the storage manager140, such as commands to transfer copies of data objects, metadata, andother payload data to the media agents 144.

In some embodiments, a data agent 142 may be distributed between theclient computing device 102 and storage manager 140 (and any otherintermediate components) or may be deployed from a remote location orits functions approximated by a remote process that performs some or allof the functions of data agent 142. In addition, a data agent 142 mayperform some functions provided by a media agent 144, or may performother functions such as encryption and deduplication.

As indicated, each data agent 142 may be specialized for a particularapplication 110, and the system can employ multiple application-specificdata agents 142, each of which may perform information managementoperations (e.g., perform backup, migration, and data recovery)associated with a different application 110. For instance, differentindividual data agents 142 may be designed to handle Microsoft Exchangedata, Lotus Notes data, Microsoft Windows file system data, MicrosoftActive Directory Objects data, SQL Server data, SharePoint data, Oracledatabase data, SAP database data, virtual machines and/or associateddata, and other types of data.

A file system data agent, for example, may handle data files and/orother file system information. If a client computing device 102 has twoor more types of data, a specialized data agent 142 may be used for eachdata type to copy, archive, migrate, and restore the client computingdevice 102 data. For example, to backup, migrate, and/or restore all ofthe data on a Microsoft Exchange server, the client computing device 102may use a Microsoft Exchange Mailbox data agent 142 to backup theExchange mailboxes, a Microsoft Exchange Database data agent 142 tobackup the Exchange databases, a Microsoft Exchange Public Folder dataagent 142 to backup the Exchange Public Folders, and a Microsoft WindowsFile System data agent 142 to backup the file system of the clientcomputing device 102. In such embodiments, these specialized data agents142 may be treated as four separate data agents 142 even though theyoperate on the same client computing device 102.

Other embodiments may employ one or more generic data agents 142 thatcan handle and process data from two or more different applications 110,or that can handle and process multiple data types, instead of or inaddition to using specialized data agents 142. For example, one genericdata agent 142 may be used to back up, migrate and restore MicrosoftExchange Mailbox data and Microsoft Exchange Database data while anothergeneric data agent may handle Microsoft Exchange Public Folder data andMicrosoft Windows File System data.

Each data agent 142 may be configured to access data and/or metadatastored in the primary storage device(s) 104 associated with the dataagent 142 and process the data as appropriate. For example, during asecondary copy operation, the data agent 142 may arrange or assemble thedata and metadata into one or more files having a certain format (e.g.,a particular backup or archive format) before transferring the file(s)to a media agent 144 or other component. The file(s) may include a listof files or other metadata. Each data agent 142 can also assist inrestoring data or metadata to primary storage devices 104 from asecondary copy 116. For instance, the data agent 142 may operate inconjunction with the storage manager 140 and one or more of the mediaagents 144 to restore data from secondary storage device(s) 108.

Media Agents

As indicated above with respect to FIG. 1A, off-loading certainresponsibilities from the client computing devices 102 to intermediatecomponents such as the media agent(s) 144 can provide a number ofbenefits including improved client computing device 102 operation,faster secondary copy operation performance, and enhanced scalability.In one specific example which will be discussed below in further detail,the media agent 144 can act as a local cache of copied data and/ormetadata that it has stored to the secondary storage device(s) 108,providing improved restore capabilities.

Generally speaking, a media agent 144 may be implemented as a softwaremodule that manages, coordinates, and facilitates the transmission ofdata, as directed by the storage manager 140, between a client computingdevice 102 and one or more secondary storage devices 108. Whereas thestorage manager 140 controls the operation of the information managementsystem 100, the media agent 144 generally provides a portal to secondarystorage devices 108. For instance, other components in the systeminteract with the media agents 144 to gain access to data stored on thesecondary storage devices 108, whether it be for the purposes ofreading, writing, modifying, or deleting data. Moreover, as will bedescribed further, media agents 144 can generate and store informationrelating to characteristics of the stored data and/or metadata, or cangenerate and store other types of information that generally providesinsight into the contents of the secondary storage devices 108.

Media agents 144 can comprise separate nodes in the informationmanagement system 100 (e.g., nodes that are separate from the clientcomputing devices 102, storage manager 140, and/or secondary storagedevices 108). In general, a node within the information managementsystem 100 can be a logically and/or physically separate component, andin some cases is a component that is individually addressable orotherwise identifiable. In addition, each media agent 144 may operate ona dedicated secondary storage computing device 106 in some cases, whilein other embodiments a plurality of media agents 144 operate on the samesecondary storage computing device 106.

A media agent 144 (and corresponding media agent database 152) may beconsidered to be “associated with” a particular secondary storage device108 if that media agent 144 is capable of one or more of: routing and/orstoring data to the particular secondary storage device 108,coordinating the routing and/or storing of data to the particularsecondary storage device 108, retrieving data from the particularsecondary storage device 108, coordinating the retrieval of data from aparticular secondary storage device 108, and modifying and/or deletingdata retrieved from the particular secondary storage device 108.

While media agent(s) 144 are generally associated with one or moresecondary storage devices 108, one or more media agents 144 in certainembodiments are physically separate from the secondary storage devices108. For instance, the media agents 144 may operate on secondary storagecomputing devices 106 having different housings or packages than thesecondary storage devices 108. In one example, a media agent 144operates on a first server computer and is in communication with asecondary storage device(s) 108 operating in a separate, rack-mountedRAID-based system.

Where the information management system 100 includes multiple mediaagents 144 (see, e.g., FIG. 1D), a first media agent 144 may providefailover functionality for a second, failed media agent 144. Inaddition, media agents 144 can be dynamically selected for storageoperations to provide load balancing. Failover and load balancing aredescribed in greater detail below.

In operation, a media agent 144 associated with a particular secondarystorage device 108 may instruct the secondary storage device 108 toperform an information management operation. For instance, a media agent144 may instruct a tape library to use a robotic arm or other retrievalmeans to load or eject a certain storage media, and to subsequentlyarchive, migrate, or retrieve data to or from that media, e.g., for thepurpose of restoring the data to a client computing device 102. Asanother example, a secondary storage device 108 may include an array ofhard disk drives or solid state drives organized in a RAIDconfiguration, and the media agent 144 may forward a logical unit number(LUN) and other appropriate information to the array, which uses thereceived information to execute the desired storage operation. The mediaagent 144 may communicate with a secondary storage device 108 via asuitable communications link, such as a SCSI or Fiber Channel link.

As shown, each media agent 144 may maintain an associated media agentdatabase 152. The media agent database 152 may be stored in a disk orother storage device (not shown) that is local to the secondary storagecomputing device 106 on which the media agent 144 operates. In othercases, the media agent database 152 is stored remotely from thesecondary storage computing device 106.

The media agent database 152 can include, among other things, an index153 (see, e.g., FIG. 1C), which comprises information generated duringsecondary copy operations and other storage or information managementoperations. The index 153 provides a media agent 144 or other componentwith a fast and efficient mechanism for locating secondary copies 116 orother data stored in the secondary storage devices 108. In some cases,the index 153 does not form a part of and is instead separate from themedia agent database 152.

A media agent index 153 or other data structure associated with theparticular media agent 144 may include information about the storeddata. For instance, for each secondary copy 116, the index 153 mayinclude metadata such as a list of the data objects (e.g.,files/subdirectories, database objects, mailbox objects, etc.), a pathto the secondary copy 116 on the corresponding secondary storage device108, location information indicating where the data objects are storedin the secondary storage device 108, when the data objects were createdor modified, etc. Thus, the index 153 includes metadata associated withthe secondary copies 116 that is readily available for use withouthaving to be first retrieved from the secondary storage device 108. Inyet further embodiments, some or all of the information in index 153 mayinstead or additionally be stored along with the secondary copies ofdata in a secondary storage device 108. In some embodiments, thesecondary storage devices 108 can include sufficient information toperform a “bare metal restore”, where the operating system of a failedclient computing device 102 or other restore target is automaticallyrebuilt as part of a restore operation.

Because the index 153 maintained in the media agent database 152 mayoperate as a cache, it can also be referred to as “an index cache.” Insuch cases, information stored in the index cache 153 typicallycomprises data that reflects certain particulars about storageoperations that have occurred relatively recently. After some triggeringevent, such as after a certain period of time elapses, or the indexcache 153 reaches a particular size, the index cache 153 may be copiedor migrated to a secondary storage device(s) 108. This information mayneed to be retrieved and uploaded back into the index cache 153 orotherwise restored to a media agent 144 to facilitate retrieval of datafrom the secondary storage device(s) 108. In some embodiments, thecached information may include format or containerization informationrelated to archives or other files stored on the storage device(s) 108.In this manner, the index cache 153 allows for accelerated restores.

In some alternative embodiments the media agent 144 generally acts as acoordinator or facilitator of storage operations between clientcomputing devices 102 and corresponding secondary storage devices 108,but does not actually write the data to the secondary storage device108. For instance, the storage manager 140 (or the media agent 144) mayinstruct a client computing device 102 and secondary storage device 108to communicate with one another directly. In such a case the clientcomputing device 102 transmits the data directly or via one or moreintermediary components to the secondary storage device 108 according tothe received instructions, and vice versa. In some such cases, the mediaagent 144 may still receive, process, and/or maintain metadata relatedto the storage operations. Moreover, in these embodiments, the payloaddata can flow through the media agent 144 for the purposes of populatingthe index cache 153 maintained in the media agent database 152, but notfor writing to the secondary storage device 108.

The media agent 144 and/or other components such as the storage manager140 may in some cases incorporate additional functionality, such as dataclassification, content indexing, deduplication, encryption,compression, and the like. Further details regarding these and otherfunctions are described below.

Distributed, Scalable Architecture

As described, certain functions of the information management system 100can be distributed amongst various physical and/or logical components inthe system. For instance, one or more of the storage manager 140, dataagents 142, and media agents 144 may operate on computing devices thatare physically separate from one another. This architecture can providea number of benefits.

For instance, hardware and software design choices for each distributedcomponent can be targeted to suit its particular function. The secondarycomputing devices 106 on which the media agents 144 operate can betailored for interaction with associated secondary storage devices 108and provide fast index cache operation, among other specific tasks.Similarly, the client computing device(s) 102 can be selected toeffectively service the applications 110 thereon, in order toefficiently produce and store primary data 112.

Moreover, in some cases, one or more of the individual components in theinformation management system 100 can be distributed to multiple,separate computing devices. As one example, for large file systems wherethe amount of data stored in the management database 146 is relativelylarge, the database 146 may be migrated to or otherwise reside on aspecialized database server (e.g., an SQL server) separate from a serverthat implements the other functions of the storage manager 140. Thisdistributed configuration can provide added protection because thedatabase 146 can be protected with standard database utilities (e.g.,SQL log shipping or database replication) independent from otherfunctions of the storage manager 140. The database 146 can beefficiently replicated to a remote site for use in the event of adisaster or other data loss at the primary site. Or the database 146 canbe replicated to another computing device within the same site, such asto a higher performance machine in the event that a storage manager hostdevice can no longer service the needs of a growing informationmanagement system 100.

The distributed architecture also provides both scalability andefficient component utilization. FIG. 1D shows an embodiment of theinformation management system 100 including a plurality of clientcomputing devices 102 and associated data agents 142 as well as aplurality of secondary storage computing devices 106 and associatedmedia agents 144.

Additional components can be added or subtracted based on the evolvingneeds of the information management system 100. For instance, dependingon where bottlenecks are identified, administrators can add additionalclient computing devices 102, secondary storage computing devices 106(and corresponding media agents 144), and/or secondary storage devices108. Moreover, where multiple fungible components are available, loadbalancing can be implemented to dynamically address identifiedbottlenecks. As an example, the storage manager 140 may dynamicallyselect which media agents 144 and/or secondary storage devices 108 touse for storage operations based on a processing load analysis of themedia agents 144 and/or secondary storage devices 108, respectively.

Moreover, each client computing device 102 in some embodiments cancommunicate with, among other components, any of the media agents 144,e.g., as directed by the storage manager 140. And each media agent 144may be able to communicate with, among other components, any of thesecondary storage devices 108, e.g., as directed by the storage manager140. Thus, operations can be routed to the secondary storage devices 108in a dynamic and highly flexible manner, to provide load balancing,failover, and the like. Further examples of scalable systems capable ofdynamic storage operations, and of systems capable of performing loadbalancing and fail over are provided in U.S. Pat. No. 7,246,207, whichis incorporated by reference herein.

In alternative configurations, certain components are not distributedand may instead reside and execute on the same computing device. Forexample, in some embodiments, one or more data agents 142 and thestorage manager 140 operate on the same client computing device 102. Inanother embodiment, one or more data agents 142 and one or more mediaagents 144 operate on a single computing device.

Exemplary Types of Information Management Operations

In order to protect and leverage stored data, the information managementsystem 100 can be configured to perform a variety of informationmanagement operations. As will be described, these operations cangenerally include secondary copy and other data movement operations,processing and data manipulation operations, analysis, reporting, andmanagement operations. The operations described herein may be performedon any type of computing device, e.g., between two computers connectedvia a LAN, to a mobile client telecommunications device connected to aserver via a WLAN, to any manner of client computing device coupled to acloud storage target, etc., without limitation.

Data Movement Operations

Data movement operations according to certain embodiments are generallyoperations that involve the copying or migration of data (e.g., payloaddata) between different locations in the information management system100 in an original/native and/or one or more different formats. Forexample, data movement operations can include operations in which storeddata is copied, migrated, or otherwise transferred from one or morefirst storage devices to one or more second storage devices, such asfrom primary storage device(s) 104 to secondary storage device(s) 108,from secondary storage device(s) 108 to different secondary storagedevice(s) 108, from secondary storage devices 108 to primary storagedevices 104, or from primary storage device(s) 104 to different primarystorage device(s) 104.

Data movement operations can include by way of example, backupoperations, archive operations, information lifecycle managementoperations such as hierarchical storage management operations,replication operations (e.g., continuous data replication operations),snapshot operations, deduplication or single-instancing operations,auxiliary copy operations, and the like. As will be discussed, some ofthese operations involve the copying, migration or other movement ofdata, without actually creating multiple, distinct copies. Nonetheless,some or all of these operations are referred to as “copy” operations forsimplicity.

Backup Operations

A backup operation creates a copy of a version of data (e.g., one ormore files or other data units) in primary data 112 at a particularpoint in time. Each subsequent backup copy may be maintainedindependently of the first. Further, a backup copy in some embodimentsis generally stored in a form that is different than the native format,e.g., a backup format. This can be in contrast to the version in primarydata 112 from which the backup copy is derived, and which may instead bestored in a native format of the source application(s) 110. In variouscases, backup copies can be stored in a format in which the data iscompressed, encrypted, deduplicated, and/or otherwise modified from theoriginal application format. For example, a backup copy may be stored ina backup format that facilitates compression and/or efficient long-termstorage.

Backup copies can have relatively long retention periods as compared toprimary data 112, and may be stored on media with slower retrieval timesthan primary data 112 and certain other types of secondary copies 116.On the other hand, backups may have relatively shorter retention periodsthan some other types of secondary copies 116, such as archive copies(described below). Backups may sometimes be stored at on offsitelocation.

Backup operations can include full backups, differential backups,incremental backups, “synthetic full” backups, and/or creating a“reference copy.” A full backup (or “standard full backup”) in someembodiments is generally a complete image of the data to be protected.However, because full backup copies can consume a relatively largeamount of storage, it can be useful to use a full backup copy as abaseline and only store changes relative to the full backup copy forsubsequent backup copies.

For instance, a differential backup operation (or cumulative incrementalbackup operation) tracks and stores changes that have occurred since thelast full backup. Differential backups can grow quickly in size, but canprovide relatively efficient restore times because a restore can becompleted in some cases using only the full backup copy and the latestdifferential copy.

An incremental backup operation generally tracks and stores changessince the most recent backup copy of any type, which can greatly reducestorage utilization. In some cases, however, restore times can berelatively long in comparison to full or differential backups becausecompleting a restore operation may involve accessing a full backup inaddition to multiple incremental backups.

Synthetic full backups generally consolidate data without directlybacking up data from the client computing device. A synthetic fullbackup is created from the most recent full backup (i.e., standard orsynthetic) and subsequent incremental and/or differential backups. Theresulting synthetic full backup is identical to what would have beencreated had the last backup for the subclient been a standard fullbackup. Unlike standard full, incremental, and differential backups, asynthetic full backup does not actually transfer data from a clientcomputer to the backup media, because it operates as a backupconsolidator. A synthetic full backup extracts the index data of eachparticipating subclient. Using this index data and the previously backedup user data images, it builds new full backup images, one for eachsubclient. The new backup images consolidate the index and user datastored in the related incremental, differential, and previous fullbackups, in some embodiments creating an archive file at the subclientlevel.

Any of the above types of backup operations can be at the volume-level,file-level, or block-level. Volume level backup operations generallyinvolve the copying of a data volume (e.g., a logical disk or partition)as a whole. In a file-level backup, the information management system100 may generally track changes to individual files, and includes copiesof files in the backup copy. In the case of a block-level backup, filesare broken into constituent blocks, and changes are tracked at theblock-level. Upon restore, the information management system 100reassembles the blocks into files in a transparent fashion.

Far less data may actually be transferred and copied to the secondarystorage devices 108 during a file-level copy than a volume-level copy.Likewise, a block-level copy may involve the transfer of less data thana file-level copy, resulting in faster execution times. However,restoring a relatively higher-granularity copy can result in longerrestore times. For instance, when restoring a block-level copy, theprocess of locating constituent blocks can sometimes result in longerrestore times as compared to file-level backups. Similar to backupoperations, the other types of secondary copy operations describedherein can also be implemented at either the volume-level, file-level,or block-level.

For example, in some embodiments, a reference copy may comprisecopy(ies) of selected objects from backed up data, typically to helporganize data by keeping contextual information from multiple sourcestogether, and/or help retain specific data for a longer period of time,such as for legal hold needs. A reference copy generally maintains dataintegrity, and when the data is restored, it may be viewed in the sameformat as the source data. In some embodiments, a reference copy isbased on a specialized client, individual subclient and associatedinformation management policies (e.g., storage policy, retention policy,etc.) that are administered within information management system 100.

Archive Operations

Because backup operations generally involve maintaining a version of thecopied data in primary data 112 and also maintaining backup copies insecondary storage device(s) 108, they can consume significant storagecapacity. To help reduce storage consumption, an archive operationaccording to certain embodiments creates a secondary copy 116 by bothcopying and removing source data. Or, seen another way, archiveoperations can involve moving some or all of the source data to thearchive destination. Thus, data satisfying criteria for removal (e.g.,data of a threshold age or size) may be removed from source storage. Thesource data may be primary data 112 or a secondary copy 116, dependingon the situation. As with backup copies, archive copies can be stored ina format in which the data is compressed, encrypted, deduplicated,and/or otherwise modified from the format of the original application orsource copy. In addition, archive copies may be retained for relativelylong periods of time (e.g., years) and, in some cases, are neverdeleted. Archive copies are generally retained for longer periods oftime than backup copies, for example. In certain embodiments, archivecopies may be made and kept for extended periods in order to meetcompliance regulations.

Moreover, when primary data 112 is archived, in some cases thecorresponding primary data 112 or a portion thereof is deleted whencreating the archive copy. Thus, archiving can serve the purpose offreeing up space in the primary storage device(s) 104 and easing thedemand on computational resources on client computing device 102.Similarly, when a secondary copy 116 is archived, the secondary copy 116may be deleted, and an archive copy can therefore serve the purpose offreeing up space in secondary storage device(s) 108. In contrast, sourcecopies often remain intact when creating backup copies. Examples ofcompatible data archiving operations are provided in U.S. Pat. No.7,107,298, which is incorporated by reference herein.

Snapshot Operations

Snapshot operations can provide a relatively lightweight, efficientmechanism for protecting data. From an end-user viewpoint, a snapshotmay be thought of as an “instant” image of the primary data 112 at agiven point in time, and may include state and/or status informationrelative to an application that creates/manages the primary data. In oneembodiment, a snapshot may generally capture the directory structure ofan object in primary data 112 such as a file or volume or other data setat a particular moment in time and may also preserve file attributes andcontents. A snapshot in some cases is created relatively quickly, e.g.,substantially instantly, using a minimum amount of file space, but maystill function as a conventional file system backup.

A “hardware snapshot” (or “hardware-based snapshot”) operation can be asnapshot operation where a target storage device (e.g., a primarystorage device 104 or a secondary storage device 108) performs thesnapshot operation in a self-contained fashion, substantiallyindependently, using hardware, firmware and/or software operating on thestorage device itself. For instance, the storage device may be capableof performing snapshot operations upon request, generally withoutintervention or oversight from any of the other components in theinformation management system 100. In this manner, hardware snapshotscan off-load other components of information management system 100 fromprocessing involved in snapshot creation and management.

A “software snapshot” (or “software-based snapshot”) operation, on theother hand, can be a snapshot operation in which one or more othercomponents in information management system 100 (e.g., client computingdevices 102, data agents 142, etc.) implement a software layer thatmanages the snapshot operation via interaction with the target storagedevice. For instance, the component executing the snapshot managementsoftware layer may derive a set of pointers and/or data that representsthe snapshot. The snapshot management software layer may then transmitthe same to the target storage device, along with appropriateinstructions for writing the snapshot.

Some types of snapshots do not actually create another physical copy ofall the data as it existed at the particular point in time, but maysimply create pointers that are able to map files and directories tospecific memory locations (e.g., to specific disk blocks) where the dataresides, as it existed at the particular point in time. For example, asnapshot copy may include a set of pointers derived from the file systemor from an application. In some other cases, the snapshot may be createdat the block-level, such that creation of the snapshot occurs withoutawareness of the file system. Each pointer points to a respective storeddata block, so that collectively, the set of pointers reflect thestorage location and state of the data object (e.g., file(s) orvolume(s) or data set(s)) at a particular point in time when thesnapshot copy was created.

An initial snapshot may use only a small amount of disk space needed torecord a mapping or other data structure representing or otherwisetracking the blocks that correspond to the current state of the filesystem. Additional disk space is usually required only when files anddirectories are modified later on. Furthermore, when files are modified,typically only the pointers which map to blocks are copied, not theblocks themselves. In some embodiments, for example in the case of“copy-on-write” snapshots, when a block changes in primary storage, theblock is copied to secondary storage or cached in primary storage beforethe block is overwritten in primary storage, and the pointer to thatblock changed to reflect the new location of that block. The snapshotmapping of file system data may also be updated to reflect the changedblock(s) at that particular point in time. In some other cases, asnapshot includes a full physical copy of all or substantially all ofthe data represented by the snapshot. Further examples of snapshotoperations are provided in U.S. Pat. No. 7,529,782, which isincorporated by reference herein.

A snapshot copy in many cases can be made quickly and withoutsignificantly impacting primary computing resources because largeamounts of data need not be copied or moved. In some embodiments, asnapshot may exist as a virtual file system, parallel to the actual filesystem. Users in some cases gain read-only access to the record of filesand directories of the snapshot. By electing to restore primary data 112from a snapshot taken at a given point in time, users may also returnthe current file system to the state of the file system that existedwhen the snapshot was taken.

Replication Operations

Another type of secondary copy operation is a replication operation.Some types of secondary copies 116 are used to periodically captureimages of primary data 112 at particular points in time (e.g., backups,archives, and snapshots). However, it can also be useful for recoverypurposes to protect primary data 112 in a more continuous fashion, byreplicating the primary data 112 substantially as changes occur. In somecases a replication copy can be a mirror copy, for instance, wherechanges made to primary data 112 are mirrored or substantiallyimmediately copied to another location (e.g., to secondary storagedevice(s) 108). By copying each write operation to the replication copy,two storage systems are kept synchronized or substantially synchronizedso that they are virtually identical at approximately the same time.Where entire disk volumes are mirrored, however, mirroring can requiresignificant amount of storage space and utilizes a large amount ofprocessing resources.

According to some embodiments storage operations are performed onreplicated data that represents a recoverable state, or “known goodstate” of a particular application running on the source system. Forinstance, in certain embodiments, known good replication copies may beviewed as copies of primary data 112. This feature allows the system todirectly access, copy, restore, backup or otherwise manipulate thereplication copies as if the data were the “live” primary data 112. Thiscan reduce access time, storage utilization, and impact on sourceapplications 110, among other benefits. Based on known good stateinformation, the information management system 100 can replicatesections of application data that represent a recoverable state ratherthan rote copying of blocks of data. Examples of compatible replicationoperations (e.g., continuous data replication) are provided in U.S. Pat.No. 7,617,262, which is incorporated by reference herein.

Deduplication/Single-Instancing Operations

Another type of data movement operation is deduplication orsingle-instance storage, which is useful to reduce the amount ofnon-primary data. For instance, some or all of the above-describedsecondary storage operations can involve deduplication in some fashion.New data is read, broken down into portions (e.g., sub-file levelblocks, files, etc.) of a selected granularity, compared with blocksthat are already in secondary storage, and only the new blocks arestored. Blocks that already exist are represented as pointers to thealready stored data.

In order to streamline the comparison process, the informationmanagement system 100 may calculate and/or store signatures (e.g.,hashes or cryptographically unique IDs) corresponding to the individualdata blocks in a database and compare the signatures instead ofcomparing entire data blocks. In some cases, only a single instance ofeach element is stored, and deduplication operations may therefore bereferred to interchangeably as “single-instancing” operations. Dependingon the implementation, however, deduplication or single-instancingoperations can store more than one instance of certain data blocks, butnonetheless significantly reduce data redundancy. Depending on theembodiment, deduplication blocks can be of fixed or variable length.Using variable length blocks can provide enhanced deduplication byresponding to changes in the data stream, but can involve complexprocessing. In some cases, the information management system 100utilizes a technique for dynamically aligning deduplication blocks(e.g., fixed-length blocks) based on changing content in the datastream, as described in U.S. Pat. No. 8,364,652, which is incorporatedby reference herein.

The information management system 100 can perform deduplication in avariety of manners at a variety of locations in the informationmanagement system 100. For instance, in some embodiments, theinformation management system 100 implements “target-side” deduplicationby deduplicating data (e.g., secondary copies 116) stored in thesecondary storage devices 108. In some such cases, the media agents 144are generally configured to manage the deduplication process. Forinstance, one or more of the media agents 144 maintain a correspondingdeduplication database that stores deduplication information (e.g.,datablock signatures). Examples of such a configuration are provided inU.S. Pat. Pub. No. 2012/0150826, which is incorporated by referenceherein. Instead of or in combination with “target-side” deduplication,deduplication can also be performed on the “source-side” (or“client-side”), e.g., to reduce the amount of traffic between the mediaagents 144 and the client computing device(s) 102 and/or reduceredundant data stored in the primary storage devices 104. According tovarious implementations, one or more of the storage devices of thetarget-side and/or source-side of an operation can be cloud-basedstorage devices. Thus, the target-side and/or source-side deduplicationcan be cloud-based deduplication. In particular, as discussedpreviously, the storage manager 140 may communicate with othercomponents within the information management system 100 via networkprotocols and cloud service provider APIs to facilitate cloud-baseddeduplication/single instancing. Examples of such deduplicationtechniques are provided in U.S. Pat. Pub. No. 2012/0150818, which isincorporated by reference herein. Some other compatiblededuplication/single instancing techniques are described in U.S. Pat.Pub. Nos. 2006/0224846 and 2009/0319534, which are incorporated byreference herein.

Information Lifecycle Management and Hierarchical Storage ManagementOperations

In some embodiments, files and other data over their lifetime move frommore expensive, quick access storage to less expensive, slower accessstorage. Operations associated with moving data through various tiers ofstorage are sometimes referred to as information lifecycle management(ILM) operations.

One type of ILM operation is a hierarchical storage management (HSM)operation. A HSM operation is generally an operation for automaticallymoving data between classes of storage devices, such as betweenhigh-cost and low-cost storage devices. For instance, an HSM operationmay involve movement of data from primary storage devices 104 tosecondary storage devices 108, or between tiers of secondary storagedevices 108. With each tier, the storage devices may be progressivelyrelatively cheaper, have relatively slower access/restore times, etc.For example, movement of data between tiers may occur as data becomesless important over time.

In some embodiments, an HSM operation is similar to an archive operationin that creating an HSM copy may (though not always) involve deletingsome of the source data, e.g., according to one or more criteria relatedto the source data. For example, an HSM copy may include data fromprimary data 112 or a secondary copy 116 that is larger than a givensize threshold or older than a given age threshold and that is stored ina backup format.

Often, and unlike some types of archive copies, HSM data that is removedor aged from the source is replaced by a logical reference pointer orstub. The reference pointer or stub can be stored in the primary storagedevice 104 (or other source storage device, such as a secondary storagedevice 108) to replace the deleted source data and to point to orotherwise indicate the new location in a secondary storage device 108.

According to one example, files are generally moved between higher andlower cost storage depending on how often the files are accessed. When auser requests access to the HSM data that has been removed or migrated,the information management system 100 uses the stub to locate the dataand may make recovery of the data appear transparent, even though theHSM data may be stored at a location different from other source data.In this manner, the data appears to the user (e.g., in file systembrowsing windows and the like) as if it still resides in the sourcelocation (e.g., in a primary storage device 104). The stub may alsoinclude some metadata associated with the corresponding data, so that afile system and/or application can provide some information about thedata object and/or a limited-functionality version (e.g., a preview) ofthe data object.

An HSM copy may be stored in a format other than the native applicationformat (e.g., where the data is compressed, encrypted, deduplicated,and/or otherwise modified from the original native application format).In some cases, copies which involve the removal of data from sourcestorage and the maintenance of stub or other logical referenceinformation on source storage may be referred to generally as “on-linearchive copies”. On the other hand, copies which involve the removal ofdata from source storage without the maintenance of stub or otherlogical reference information on source storage may be referred to as“off-line archive copies”. Examples of HSM and ILM techniques areprovided in U.S. Pat. No. 7,343,453, which is incorporated by referenceherein.

Auxiliary Copy and Disaster Recovery Operations

An auxiliary copy is generally a copy operation in which a copy iscreated of an existing secondary copy 116. For instance, an initialsecondary copy 116 may be generated using or otherwise be derived fromprimary data 112 (or other data residing in the secondary storagesubsystem 118), whereas an auxiliary copy is generated from the initialsecondary copy 116. Auxiliary copies can be used to create additionalstandby copies of data and may reside on different secondary storagedevices 108 than the initial secondary copies 116. Thus, auxiliarycopies can be used for recovery purposes if initial secondary copies 116become unavailable. Exemplary compatible auxiliary copy techniques aredescribed in further detail in U.S. Pat. No. 8,230,195, which isincorporated by reference herein.

The information management system 100 may also perform disaster recoveryoperations that make or retain disaster recovery copies, often assecondary, high-availability disk copies. The information managementsystem 100 may create secondary disk copies and store the copies atdisaster recovery locations using auxiliary copy or replicationoperations, such as continuous data replication technologies. Dependingon the particular data protection goals, disaster recovery locations canbe remote from the client computing devices 102 and primary storagedevices 104, remote from some or all of the secondary storage devices108, or both.

Data Analysis, Reporting, and Management Operations

Data analysis, reporting, and management operations can be differentthan data movement operations in that they do not necessarily involvethe copying, migration or other transfer of data (e.g., primary data 112or secondary copies 116) between different locations in the system. Forinstance, data analysis operations may involve processing (e.g., offlineprocessing) or modification of already stored primary data 112 and/orsecondary copies 116. However, in some embodiments data analysisoperations are performed in conjunction with data movement operations.Some data analysis operations include content indexing operations andclassification operations which can be useful in leveraging the dataunder management to provide enhanced search and other features. Otherdata analysis operations such as compression and encryption can providedata reduction and security benefits, respectively.

Classification Operations/Content Indexing

In some embodiments, the information management system 100 analyzes andindexes characteristics, content, and metadata associated with theprimary data 112 and/or secondary copies 116. The content indexing canbe used to identify files or other data objects having pre-definedcontent (e.g., user-defined keywords or phrases, other keywords/phrasesthat are not defined by a user, etc.), and/or metadata (e.g., emailmetadata such as “to”, “from”, “cc”, “bcc”, attachment name, receivedtime, etc.).

The information management system 100 generally organizes and cataloguesthe results in a content index, which may be stored within the mediaagent database 152, for example. The content index can also include thestorage locations of (or pointer references to) the indexed data in theprimary data 112 or secondary copies 116, as appropriate. The resultsmay also be stored, in the form of a content index database orotherwise, elsewhere in the information management system 100 (e.g., inthe primary storage devices 104, or in the secondary storage device108). Such index data provides the storage manager 140 or anothercomponent with an efficient mechanism for locating primary data 112and/or secondary copies 116 of data objects that match particularcriteria.

For instance, search criteria can be specified by a user through userinterface 158 of the storage manager 140. In some cases, the informationmanagement system 100 analyzes data and/or metadata in secondary copies116 to create an “off-line” content index, without significantlyimpacting the performance of the client computing devices 102. Dependingon the embodiment, the system can also implement “on-line” contentindexing, e.g., of primary data 112. Examples of compatible contentindexing techniques are provided in U.S. Pat. No. 8,170,995, which isincorporated by reference herein.

One or more components can be configured to scan data and/or associatedmetadata for classification purposes to populate a database (or otherdata structure) of information, which can be referred to as a “dataclassification database” or a “metabase”. Depending on the embodiment,the data classification database(s) can be organized in a variety ofdifferent ways, including centralization, logical sub-divisions, and/orphysical sub-divisions. For instance, one or more centralized dataclassification databases may be associated with different subsystems ortiers within the information management system 100. As an example, theremay be a first centralized metabase associated with the primary storagesubsystem 117 and a second centralized metabase associated with thesecondary storage subsystem 118. In other cases, there may be one ormore metabases associated with individual components, e.g., clientcomputing devices 102 and/or media agents 144. In some embodiments, adata classification database (metabase) may reside as one or more datastructures within management database 146, or may be otherwiseassociated with storage manager 140.

In some cases, the metabase(s) may be included in separate database(s)and/or on separate storage device(s) from primary data 112 and/orsecondary copies 116, such that operations related to the metabase donot significantly impact performance on other components in theinformation management system 100. In other cases, the metabase(s) maybe stored along with primary data 112 and/or secondary copies 116. Filesor other data objects can be associated with identifiers (e.g., tagentries, etc.) in the media agent 144 (or other indices) to facilitatesearches of stored data objects. Among a number of other benefits, themetabase can also allow efficient, automatic identification of files orother data objects to associate with secondary copy or other informationmanagement operations (e.g., in lieu of scanning an entire file system).Examples of compatible metabases and data classification operations areprovided in U.S. Pat. Nos. 8,229,954 and 7,747,579, which areincorporated by reference herein.

Encryption Operations

The information management system 100 in some cases is configured toprocess data (e.g., files or other data objects, secondary copies 116,etc.), according to an appropriate encryption algorithm (e.g., Blowfish,Advanced Encryption Standard [AES], Triple Data Encryption Standard[3-DES], etc.) to limit access and provide data security in theinformation management system 100. The information management system 100in some cases encrypts the data at the client level, such that theclient computing devices 102 (e.g., the data agents 142) encrypt thedata prior to forwarding the data to other components, e.g., beforesending the data to media agents 144 during a secondary copy operation.In such cases, the client computing device 102 may maintain or haveaccess to an encryption key or passphrase for decrypting the data uponrestore. Encryption can also occur when creating copies of secondarycopies, e.g., when creating auxiliary copies or archive copies. In yetfurther embodiments, the secondary storage devices 108 can implementbuilt-in, high performance hardware encryption.

Management and Reporting Operations

Certain embodiments leverage the integrated, ubiquitous nature of theinformation management system 100 to provide useful system-widemanagement and reporting functions. Examples of some compatiblemanagement and reporting techniques are provided in U.S. Pat. No.7,343,453, which is incorporated by reference herein.

Operations management can generally include monitoring and managing thehealth and performance of information management system 100 by, withoutlimitation, performing error tracking, generating granularstorage/performance metrics (e.g., job success/failure information,deduplication efficiency, etc.), generating storage modeling and costinginformation, and the like. As an example, a storage manager 140 or othercomponent in the information management system 100 may analyze trafficpatterns and suggest and/or automatically route data via a particularroute to minimize congestion. In some embodiments, the system cangenerate predictions relating to storage operations or storage operationinformation. Such predictions, which may be based on a trendinganalysis, may predict various network operations or resource usage, suchas network traffic levels, storage media use, use of bandwidth ofcommunication links, use of media agent components, etc. Furtherexamples of traffic analysis, trend analysis, prediction generation, andthe like are described in U.S. Pat. No. 7,343,453, which is incorporatedby reference herein.

In some configurations, a master storage manager 140 may track thestatus of storage operation cells in a hierarchy, such as the status ofjobs, system components, system resources, and other items, bycommunicating with storage managers 140 (or other components) in therespective storage operation cells. Moreover, the master storage manager140 may track the status of its associated storage operation cells andinformation management operations by receiving periodic status updatesfrom the storage managers 140 (or other components) in the respectivecells regarding jobs, system components, system resources, and otheritems. In some embodiments, a master storage manager 140 may storestatus information and other information regarding its associatedstorage operation cells and other system information in its index 150(or other location).

The master storage manager 140 or other component may also determinewhether certain storage-related criteria or other criteria aresatisfied, and perform an action or trigger event (e.g., data migration)in response to the criteria being satisfied, such as where a storagethreshold is met for a particular volume, or where inadequate protectionexists for certain data. For instance, in some embodiments, data fromone or more storage operation cells is used to dynamically andautomatically mitigate recognized risks, and/or to advise users of risksor suggest actions to mitigate these risks. For example, an informationmanagement policy may specify certain requirements (e.g., that a storagedevice should maintain a certain amount of free space, that secondarycopies should occur at a particular interval, that data should be agedand migrated to other storage after a particular period, that data on asecondary volume should always have a certain level of availability andbe restorable within a given time period, that data on a secondaryvolume may be mirrored or otherwise migrated to a specified number ofother volumes, etc.). If a risk condition or other criterion istriggered, the system may notify the user of these conditions and maysuggest (or automatically implement) an action to mitigate or otherwiseaddress the risk. For example, the system may indicate that data from aprimary copy 112 should be migrated to a secondary storage device 108 tofree space on the primary storage device 104. Examples of the use ofrisk factors and other triggering criteria are described in U.S. Pat.No. 7,343,453, which is incorporated by reference herein.

In some embodiments, the system 100 may also determine whether a metricor other indication satisfies particular storage criteria and, if so,perform an action. For example, as previously described, a storagepolicy or other definition might indicate that a storage manager 140should initiate a particular action if a storage metric or otherindication drops below or otherwise fails to satisfy specified criteriasuch as a threshold of data protection. Examples of such metrics aredescribed in U.S. Pat. No. 7,343,453, which is incorporated by referenceherein.

In some embodiments, risk factors may be quantified into certainmeasurable service or risk levels for ease of comprehension. Forexample, certain applications and associated data may be considered tobe more important by an enterprise than other data and services.Financial compliance data, for example, may be of greater importancethan marketing materials, etc. Network administrators may assignpriority values or “weights” to certain data and/or applications,corresponding to the relative importance. The level of compliance ofstorage operations specified for these applications may also be assigneda certain value. Thus, the health, impact, and overall importance of aservice may be determined, such as by measuring the compliance value andcalculating the product of the priority value and the compliance valueto determine the “service level” and comparing it to certain operationalthresholds to determine whether it is acceptable. Further examples ofthe service level determination are provided in U.S. Pat. No. 7,343,453,which is incorporated by reference herein.

The system 100 may additionally calculate data costing and dataavailability associated with information management operation cellsaccording to an embodiment of the invention. For instance, data receivedfrom the cell may be used in conjunction with hardware-relatedinformation and other information about system elements to determine thecost of storage and/or the availability of particular data in thesystem. Exemplary information generated could include how fast aparticular department is using up available storage space, how long datawould take to recover over a particular system pathway from a particularsecondary storage device, costs over time, etc. Moreover, in someembodiments, such information may be used to determine or predict theoverall cost associated with the storage of certain information. Thecost associated with hosting a certain application may be based, atleast in part, on the type of media on which the data resides, forexample. Storage devices may be assigned to a particular costcategories, for example. Further examples of costing techniques aredescribed in U.S. Pat. No. 7,343,453, which is incorporated by referenceherein.

Any of the above types of information (e.g., information related totrending, predictions, job, cell or component status, risk, servicelevel, costing, etc.) can generally be provided to users via the userinterface 158 in a single, integrated view or console (not shown). Theconsole may support a reporting capability that allows for thegeneration of a variety of reports, which may be tailored to aparticular aspect of information management. Report types may include:scheduling, event management, media management and data aging. Availablereports may also include backup history, data aging history, auxiliarycopy history, job history, library and drive, media in library, restorehistory, and storage policy, etc., without limitation. Such reports maybe specified and created at a certain point in time as a systemanalysis, forecasting, or provisioning tool. Integrated reports may alsobe generated that illustrate storage and performance metrics, risks andstorage costing information. Moreover, users may create their ownreports based on specific needs.

The integrated user interface 158 can include an option to show a“virtual view” of the system that graphically depicts the variouscomponents in the system using appropriate icons. As one example, theuser interface 158 may provide a graphical depiction of one or moreprimary storage devices 104, the secondary storage devices 108, dataagents 142 and/or media agents 144, and their relationship to oneanother in the information management system 100. The operationsmanagement functionality can facilitate planning and decision-making.For example, in some embodiments, a user may view the status of some orall jobs as well as the status of each component of the informationmanagement system 100. Users may then plan and make decisions based onthis data. For instance, a user may view high-level informationregarding storage operations for the information management system 100,such as job status, component status, resource status (e.g.,communication pathways, etc.), and other information. The user may alsodrill down or use other means to obtain more detailed informationregarding a particular component, job, or the like. Further examples ofsome reporting techniques and associated interfaces providing anintegrated view of an information management system are provided in U.S.Pat. No. 7,343,453, which is incorporated by reference herein.

The information management system 100 can also be configured to performsystem-wide e-discovery operations in some embodiments. In general,e-discovery operations provide a unified collection and searchcapability for data in the system, such as data stored in the secondarystorage devices 108 (e.g., backups, archives, or other secondary copies116). For example, the information management system 100 may constructand maintain a virtual repository for data stored in the informationmanagement system 100 that is integrated across source applications 110,different storage device types, etc. According to some embodiments,e-discovery utilizes other techniques described herein, such as dataclassification and/or content indexing.

Information Management Policies

As indicated previously, an information management policy 148 caninclude a data structure or other information source that specifies aset of parameters (e.g., criteria and rules) associated with secondarycopy and/or other information management operations.

One type of information management policy 148 is a storage policy.According to certain embodiments, a storage policy generally comprises adata structure or other information source that defines (or includesinformation sufficient to determine) a set of preferences or othercriteria for performing information management operations. Storagepolicies can include one or more of the following items: (1) what datawill be associated with the storage policy; (2) a destination to whichthe data will be stored; (3) datapath information specifying how thedata will be communicated to the destination; (4) the type of storageoperation to be performed; and (5) retention information specifying howlong the data will be retained at the destination (see, e.g., FIG. 1E).

As an illustrative example, data associated with a storage policy can belogically organized into groups. In some cases, these logical groupingscan be referred to as “sub-clients”. A sub-client may represent staticor dynamic associations of portions of a data volume. Sub-clients mayrepresent mutually exclusive portions. Thus, in certain embodiments, aportion of data may be given a label and the association is stored as astatic entity in an index, database or other storage location.Sub-clients may also be used as an effective administrative scheme oforganizing data according to data type, department within theenterprise, storage preferences, or the like. Depending on theconfiguration, sub-clients can correspond to files, folders, virtualmachines, databases, etc. In one exemplary scenario, an administratormay find it preferable to separate e-mail data from financial data usingtwo different sub-clients.

A storage policy can define where data is stored by specifying a targetor destination storage device (or group of storage devices). Forinstance, where the secondary storage device 108 includes a group ofdisk libraries, the storage policy may specify a particular disk libraryfor storing the sub-clients associated with the policy. As anotherexample, where the secondary storage devices 108 include one or moretape libraries, the storage policy may specify a particular tape libraryfor storing the sub-clients associated with the storage policy, and mayalso specify a drive pool and a tape pool defining a group of tapedrives and a group of tapes, respectively, for use in storing thesub-client data. While information in the storage policy can bestatically assigned in some cases, some or all of the information in thestorage policy can also be dynamically determined based on criteria,which can be set forth in the storage policy. For instance, based onsuch criteria, a particular destination storage device(s) (or otherparameter of the storage policy) may be determined based oncharacteristics associated with the data involved in a particularstorage operation, device availability (e.g., availability of asecondary storage device 108 or a media agent 144), network status andconditions (e.g., identified bottlenecks), user credentials, and thelike).

Datapath information can also be included in the storage policy. Forinstance, the storage policy may specify network pathways and componentsto utilize when moving the data to the destination storage device(s). Insome embodiments, the storage policy specifies one or more media agents144 for conveying data associated with the storage policy between thesource (e.g., one or more host client computing devices 102) anddestination (e.g., a particular target secondary storage device 108).

A storage policy can also specify the type(s) of operations associatedwith the storage policy, such as a backup, archive, snapshot, auxiliarycopy, or the like. Retention information can specify how long the datawill be kept, depending on organizational needs (e.g., a number of days,months, years, etc.)

Another type of information management policy 148 is a schedulingpolicy, which specifies when and how often to perform operations.Scheduling parameters may specify with what frequency (e.g., hourly,weekly, daily, event-based, etc.) or under what triggering conditionssecondary copy or other information management operations will takeplace. Scheduling policies in some cases are associated with particularcomponents, such as particular logical groupings of data associated witha storage policy (e.g., a sub-client), client computing device 102, andthe like. In one configuration, a separate scheduling policy ismaintained for particular logical groupings of data on a clientcomputing device 102. The scheduling policy specifies that those logicalgroupings are to be moved to secondary storage devices 108 every houraccording to storage policies associated with the respectivesub-clients.

When adding a new client computing device 102, administrators canmanually configure information management policies 148 and/or othersettings, e.g., via the user interface 158. However, this can be aninvolved process resulting in delays, and it may be desirable to begindata protection operations quickly, without awaiting human intervention.Thus, in some embodiments, the information management system 100automatically applies a default configuration to client computing device102. As one example, when one or more data agent(s) 142 are installed onone or more client computing devices 102, the installation script mayregister the client computing device 102 with the storage manager 140,which in turn applies the default configuration to the new clientcomputing device 102. In this manner, data protection operations canbegin substantially immediately. The default configuration can include adefault storage policy, for example, and can specify any appropriateinformation sufficient to begin data protection operations. This caninclude a type of data protection operation, scheduling information, atarget secondary storage device 108, data path information (e.g., aparticular media agent 144), and the like.

Other types of information management policies 148 are possible,including one or more audit (or security) policies. An audit policy is aset of preferences, rules and/or criteria that protect sensitive data inthe information management system 100. For example, an audit policy maydefine “sensitive objects” as files or objects that contain particularkeywords (e.g., “confidential,” or “privileged”) and/or are associatedwith particular keywords (e.g., in metadata) or particular flags (e.g.,in metadata identifying a document or email as personal, confidential,etc.). An audit policy may further specify rules for handling sensitiveobjects. As an example, an audit policy may require that a reviewerapprove the transfer of any sensitive objects to a cloud storage site,and that if approval is denied for a particular sensitive object, thesensitive object should be transferred to a local primary storage device104 instead. To facilitate this approval, the audit policy may furtherspecify how a secondary storage computing device 106 or other systemcomponent should notify a reviewer that a sensitive object is slated fortransfer.

Another type of information management policy 148 is a provisioningpolicy. A provisioning policy can include a set of preferences,priorities, rules, and/or criteria that specify how client computingdevices 102 (or groups thereof) may utilize system resources, such asavailable storage on cloud storage and/or network bandwidth. Aprovisioning policy specifies, for example, data quotas for particularclient computing devices 102 (e.g., a number of gigabytes that can bestored monthly, quarterly or annually). The storage manager 140 or othercomponents may enforce the provisioning policy. For instance, the mediaagents 144 may enforce the policy when transferring data to secondarystorage devices 108. If a client computing device 102 exceeds a quota, abudget for the client computing device 102 (or associated department) isadjusted accordingly or an alert may trigger.

While the above types of information management policies 148 have beendescribed as separate policies, one or more of these can be generallycombined into a single information management policy 148. For instance,a storage policy may also include or otherwise be associated with one ormore scheduling, audit, or provisioning policies or operationalparameters thereof. Moreover, while storage policies are typicallyassociated with moving and storing data, other policies may beassociated with other types of information management operations. Thefollowing is a non-exhaustive list of items the information managementpolicies 148 may specify:

-   -   schedules or other timing information, e.g., specifying when        and/or how often to perform information management operations;    -   the type of copy 116 (e.g., type of secondary copy) and/or copy        format (e.g., snapshot, backup, archive, HSM, etc.);    -   a location or a class or quality of storage for storing        secondary copies 116 (e.g., one or more particular secondary        storage devices 108);    -   preferences regarding whether and how to encrypt, compress,        deduplicate, or otherwise modify or transform secondary copies        116;    -   which system components and/or network pathways (e.g., preferred        media agents 144) should be used to perform secondary storage        operations;    -   resource allocation among different computing devices or other        system components used in performing information management        operations (e.g., bandwidth allocation, available storage        capacity, etc.);    -   whether and how to synchronize or otherwise distribute files or        other data objects across multiple computing devices or hosted        services; and    -   retention information specifying the length of time primary data        112 and/or secondary copies 116 should be retained, e.g., in a        particular class or tier of storage devices, or within the        information management system 100.

Policies can additionally specify or depend on a variety of historicalor current criteria that may be used to determine which rules to applyto a particular data object, system component, or information managementoperation, such as:

-   -   frequency with which primary data 112 or a secondary copy 116 of        a data object or metadata has been or is predicted to be used,        accessed, or modified;    -   time-related factors (e.g., aging information such as time since        the creation or modification of a data object);    -   deduplication information (e.g., hashes, data blocks,        deduplication block size, deduplication efficiency or other        metrics);    -   an estimated or historic usage or cost associated with different        components (e.g., with secondary storage devices 108);    -   the identity of users, applications 110, client computing        devices 102 and/or other computing devices that created,        accessed, modified, or otherwise utilized primary data 112 or        secondary copies 116;    -   a relative sensitivity (e.g., confidentiality, importance) of a        data object, e.g., as determined by its content and/or metadata;    -   the current or historical storage capacity of various storage        devices;    -   the current or historical network capacity of network pathways        connecting various components within the storage operation cell;    -   access control lists or other security information; and    -   the content of a particular data object (e.g., its textual        content) or of metadata associated with the data object.

Exemplary Storage Policy and Secondary Storage Operations

FIG. 1E includes a data flow diagram depicting performance of storageoperations by an embodiment of an information management system 100,according to an exemplary storage policy 148A. The informationmanagement system 100 includes a storage manger 140, a client computingdevice 102 having a file system data agent 142A and an email data agent142B operating thereon, a primary storage device 104, two media agents144A, 144B, and two secondary storage devices 108A, 108B: a disk library108A and a tape library 108B. As shown, the primary storage device 104includes primary data 112A, which is associated with a logical groupingof data associated with a file system, and primary data 112B, which isassociated with a logical grouping of data associated with email.Although for simplicity the logical grouping of data associated with thefile system is referred to as a file system sub-client, and the logicalgrouping of data associated with the email is referred to as an emailsub-client, the techniques described with respect to FIG. 1E can beutilized in conjunction with data that is organized in a variety ofother manners.

As indicated by the dashed box, the second media agent 144B and the tapelibrary 108B are “off-site”, and may therefore be remotely located fromthe other components in the information management system 100 (e.g., ina different city, office building, etc.). Indeed, “off-site” may referto a magnetic tape located in storage, which must be manually retrievedand loaded into a tape drive to be read. In this manner, informationstored on the tape library 108B may provide protection in the event of adisaster or other failure.

The file system sub-client and its associated primary data 112A incertain embodiments generally comprise information generated by the filesystem and/or operating system of the client computing device 102, andcan include, for example, file system data (e.g., regular files, filetables, mount points, etc.), operating system data (e.g., registries,event logs, etc.), and the like. The e-mail sub-client, on the otherhand, and its associated primary data 112B, include data generated by ane-mail application operating on the client computing device 102, and caninclude mailbox information, folder information, emails, attachments,associated database information, and the like. As described above, thesub-clients can be logical containers, and the data included in thecorresponding primary data 112A, 112B may or may not be storedcontiguously.

The exemplary storage policy 148A includes backup copy preferences (orrule set) 160, disaster recovery copy preferences rule set 162, andcompliance copy preferences or rule set 164. The backup copy rule set160 specifies that it is associated with a file system sub-client 166and an email sub-client 168. Each of these sub-clients 166, 168 areassociated with the particular client computing device 102. The backupcopy rule set 160 further specifies that the backup operation will bewritten to the disk library 108A, and designates a particular mediaagent 144A to convey the data to the disk library 108A. Finally, thebackup copy rule set 160 specifies that backup copies created accordingto the rule set 160 are scheduled to be generated on an hourly basis andto be retained for 30 days. In some other embodiments, schedulinginformation is not included in the storage policy 148A, and is insteadspecified by a separate scheduling policy.

The disaster recovery copy rule set 162 is associated with the same twosub-clients 166, 168. However, the disaster recovery copy rule set 162is associated with the tape library 108B, unlike the backup copy ruleset 160. Moreover, the disaster recovery copy rule set 162 specifiesthat a different media agent, namely 144B, will be used to convey thedata to the tape library 108B. As indicated, disaster recovery copiescreated according to the rule set 162 will be retained for 60 days, andwill be generated on a daily basis. Disaster recovery copies generatedaccording to the disaster recovery copy rule set 162 can provideprotection in the event of a disaster or other catastrophic data lossthat would affect the backup copy 116A maintained on the disk library108A.

The compliance copy rule set 164 is only associated with the emailsub-client 168, and not the file system sub-client 166. Compliancecopies generated according to the compliance copy rule set 164 willtherefore not include primary data 112A from the file system sub-client166. For instance, the organization may be under an obligation to storeand maintain copies of email data for a particular period of time (e.g.,10 years) to comply with state or federal regulations, while similarregulations do not apply to the file system data. The compliance copyrule set 164 is associated with the same tape library 108B and mediaagent 144B as the disaster recovery copy rule set 162, although adifferent storage device or media agent could be used in otherembodiments. Finally, the compliance copy rule set 164 specifies thatcopies generated under the compliance copy rule set 164 will be retainedfor 10 years, and will be generated on a quarterly basis.

At step 1, the storage manager 140 initiates a backup operationaccording to the backup copy rule set 160. For instance, a schedulingservice running on the storage manager 140 accesses schedulinginformation from the backup copy rule set 160 or a separate schedulingpolicy associated with the client computing device 102, and initiates abackup copy operation on an hourly basis. Thus, at the scheduled timeslot the storage manager 140 sends instructions to the client computingdevice 102 (i.e., to both data agent 142A and data agent 142B) to beginthe backup operation.

At step 2, the file system data agent 142A and the email data agent 142Boperating on the client computing device 102 respond to the instructionsreceived from the storage manager 140 by accessing and processing theprimary data 112A, 112B involved in the copy operation, which can befound in primary storage device 104. Because the operation is a backupcopy operation, the data agent(s) 142A, 142B may format the data into abackup format or otherwise process the data.

At step 3, the client computing device 102 communicates the retrieved,processed data to the first media agent 144A, as directed by the storagemanager 140, according to the backup copy rule set 160. In some otherembodiments, the information management system 100 may implement aload-balancing, availability-based, or other appropriate algorithm toselect from the available set of media agents 144A, 144B. Regardless ofthe manner the media agent 144A is selected, the storage manager 140 mayfurther keep a record in the storage manager database 146 of theassociation between the selected media agent 144A and the clientcomputing device 102 and/or between the selected media agent 144A andthe backup copy 116A.

The target media agent 144A receives the data from the client computingdevice 102, and at step 4 conveys the data to the disk library 108A tocreate the backup copy 116A, again at the direction of the storagemanager 140 and according to the backup copy rule set 160. The secondarystorage device 108A can be selected in other ways. For instance, themedia agent 144A may have a dedicated association with a particularsecondary storage device(s), or the storage manager 140 or media agent144A may select from a plurality of secondary storage devices, e.g.,according to availability, using one of the techniques described in U.S.Pat. No. 7,246,207, which is incorporated by reference herein.

The media agent 144A can also update its index 153 to include dataand/or metadata related to the backup copy 116A, such as informationindicating where the backup copy 116A resides on the disk library 108A,data and metadata for cache retrieval, etc. The storage manager 140 maysimilarly update its index 150 to include information relating to thestorage operation, such as information relating to the type of storageoperation, a physical location associated with one or more copiescreated by the storage operation, the time the storage operation wasperformed, status information relating to the storage operation, thecomponents involved in the storage operation, and the like. In somecases, the storage manager 140 may update its index 150 to include someor all of the information stored in the index 153 of the media agent144A. After the 30 day retention period expires, the storage manager 140instructs the media agent 144A to delete the backup copy 116A from thedisk library 108A. Indexes 150 and/or 153 are updated accordingly.

At step 5, the storage manager 140 initiates the creation of a disasterrecovery copy 116B according to the disaster recovery copy rule set 162.

At step 6, illustratively based on the instructions received from thestorage manager 140 at step 5, the specified media agent 144B retrievesthe most recent backup copy 116A from the disk library 108A.

At step 7, again at the direction of the storage manager 140 and asspecified in the disaster recovery copy rule set 162, the media agent144B uses the retrieved data to create a disaster recovery copy 116B onthe tape library 108B. In some cases, the disaster recovery copy 116B isa direct, mirror copy of the backup copy 116A, and remains in the backupformat. In other embodiments, the disaster recovery copy 116B may begenerated in some other manner, such as by using the primary data 112A,112B from the primary storage device 104 as source data. The disasterrecovery copy operation is initiated once a day and the disasterrecovery copies 116B are deleted after 60 days; indexes are updatedaccordingly when/after each information management operation isexecuted/completed.

At step 8, the storage manager 140 initiates the creation of acompliance copy 116C, according to the compliance copy rule set 164. Forinstance, the storage manager 140 instructs the media agent 144B tocreate the compliance copy 116C on the tape library 108B at step 9, asspecified in the compliance copy rule set 164. In the example, thecompliance copy 116C is generated using the disaster recovery copy 116B.In other embodiments, the compliance copy 116C is instead generatedusing either the primary data 112B corresponding to the email sub-clientor using the backup copy 116A from the disk library 108A as source data.As specified, in the illustrated example, compliance copies 116C arecreated quarterly, and are deleted after ten years, and indexes are keptup-to-date accordingly.

While not shown in FIG. 1E, at some later point in time, a restoreoperation can be initiated involving one or more of the secondary copies116A, 116B, 116C. As one example, a user may manually initiate a restoreof the backup copy 116A by interacting with the user interface 158 ofthe storage manager 140. The storage manager 140 then accesses data inits index 150 (and/or the respective storage policy 148A) associatedwith the selected backup copy 116A to identify the appropriate mediaagent 144A and/or secondary storage device 108A.

In other cases, a media agent may be selected for use in the restoreoperation based on a load balancing algorithm, an availability basedalgorithm, or other criteria. The selected media agent 144A retrievesthe data from the disk library 108A. For instance, the media agent 144Amay access its index 153 to identify a location of the backup copy 116Aon the disk library 108A, or may access location information residing onthe disk 108A itself.

When the backup copy 116A was recently created or accessed, the mediaagent 144A accesses a cached version of the backup copy 116A residing inthe index 153, without having to access the disk library 108A for someor all of the data. Once it has retrieved the backup copy 116A, themedia agent 144A communicates the data to the source client computingdevice 102. Upon receipt, the file system data agent 142A and the emaildata agent 142B may unpackage (e.g., restore from a backup format to thenative application format) the data in the backup copy 116A and restorethe unpackaged data to the primary storage device 104.

Exemplary Applications of Storage Policies

The storage manager 140 may permit a user to specify aspects of thestorage policy 148A. For example, the storage policy can be modified toinclude information governance policies to define how data should bemanaged in order to comply with a certain regulation or businessobjective. The various policies may be stored, for example, in themanagement database 146. An information governance policy may comprise aclassification policy, which is described herein. An informationgovernance policy may align with one or more compliance tasks that areimposed by regulations or business requirements. Examples of informationgovernance policies might include a Sarbanes-Oxley policy, a HIPAApolicy, an electronic discovery (E-Discovery) policy, and so on.

Information governance policies allow administrators to obtain differentperspectives on all of an organization's online and offline data,without the need for a dedicated data silo created solely for eachdifferent viewpoint. As described previously, the data storage systemsherein build a centralized index that reflects the contents of adistributed data set that spans numerous clients and storage devices,including both primary and secondary copies, and online and offlinecopies. An organization may apply multiple information governancepolicies in a top-down manner over that unified data set and indexingschema in order to permit an organization to view and manipulate thesingle data set through different lenses, each of which is adapted to aparticular compliance or business goal. Thus, for example, by applyingan E-discovery policy and a Sarbanes-Oxley policy, two different groupsof users in an organization can conduct two very different analyses ofthe same underlying physical set of data copies, which may bedistributed throughout the organization and information managementsystem.

A classification policy defines a taxonomy of classification terms ortags relevant to a compliance task and/or business objective. Aclassification policy may also associate a defined tag with aclassification rule. A classification rule defines a particularcombination of criteria, such as users who have created, accessed ormodified a document or data object; file or application types; contentor metadata keywords; clients or storage locations; dates of datacreation and/or access; review status or other status within a workflow(e.g., reviewed or un-reviewed); modification times or types ofmodifications; and/or any other data attributes in any combination,without limitation. A classification rule may also be defined usingother classification tags in the taxonomy. The various criteria used todefine a classification rule may be combined in any suitable fashion,for example, via Boolean operators, to define a complex classificationrule. As an example, an E-discovery classification policy might define aclassification tag “privileged” that is associated with documents ordata objects that (1) were created or modified by legal departmentstaff, or (2) were sent to or received from outside counsel via email,or (3) contain one of the following keywords: “privileged” or “attorney”or “counsel”, or other like terms.

One specific type of classification tag, which may be added to an indexat the time of indexing, is an entity tag. An entity tag may be, forexample, any content that matches a defined data mask format. Examplesof entity tags might include, e.g., social security numbers (e.g., anynumerical content matching the formatting mask XXX-XX-XXXX), credit cardnumbers (e.g., content having a 13-16 digit string of numbers), SKUnumbers, product numbers, etc.

A user may define a classification policy by indicating criteria,parameters or descriptors of the policy via a graphical user interface,such as a form or page with fields to be filled in, pull-down menus orentries allowing one or more of several options to be selected, buttons,sliders, hypertext links or other known user interface tools forreceiving user input, etc. For example, a user may define certain entitytags, such as a particular product number or project ID code that isrelevant in the organization. In some implementations, theclassification policy can be implemented using cloud-based techniques.For example, the storage devices may be cloud storage devices, and thestorage manager 140 may execute cloud service provider API over anetwork to classify data stored on cloud storage devices.

Exemplary Secondary Copy Formatting

The formatting and structure of secondary copies 116 can vary, dependingon the embodiment. In some cases, secondary copies 116 are formatted asa series of logical data units or “chunks” (e.g., 512 MB, 1 GB, 2 GB, 4GB, or 8 GB chunks). This can facilitate efficient communication andwriting to secondary storage devices 108, e.g., according to resourceavailability. For example, a single secondary copy 116 may be written ona chunk-by-chunk basis to a single secondary storage device 108 oracross multiple secondary storage devices 108. In some cases, users canselect different chunk sizes, e.g., to improve throughput to tapestorage devices.

Generally, each chunk can include a header and a payload. The payloadcan include files (or other data units) or subsets thereof included inthe chunk, whereas the chunk header generally includes metadata relatingto the chunk, some or all of which may be derived from the payload. Forexample, during a secondary copy operation, the media agent 144, storagemanager 140, or other component may divide the associated files intochunks and generate headers for each chunk by processing the constituentfiles. The headers can include a variety of information such as fileidentifier(s), volume(s), offset(s), or other information associatedwith the payload data items, a chunk sequence number, etc. Importantly,in addition to being stored with the secondary copy 116 on the secondarystorage device 108, the chunk headers can also be stored to the index153 of the associated media agent(s) 144 and/or the index 150. This isuseful in some cases for providing faster processing of secondary copies116 during restores or other operations. In some cases, once a chunk issuccessfully transferred to a secondary storage device 108, thesecondary storage device 108 returns an indication of receipt, e.g., tothe media agent 144 and/or storage manager 140, which may update theirrespective indexes 153, 150 accordingly. During restore, chunks may beprocessed (e.g., by the media agent 144) according to the information inthe chunk header to reassemble the files.

Data can also be communicated within the information management system100 in data channels that connect the client computing devices 102 tothe secondary storage devices 108. These data channels can be referredto as “data streams”, and multiple data streams can be employed toparallelize an information management operation, improving data transferrate, among providing other advantages. Example data formattingtechniques including techniques involving data streaming, chunking, andthe use of other data structures in creating copies (e.g., secondarycopies) are described in U.S. Pat. Nos. 7,315,923 and 8,156,086, and8,578,120, each of which is incorporated by reference herein.

FIGS. 1F and 1G are diagrams of example data streams 170 and 171,respectively, which may be employed for performing data storageoperations. Referring to FIG. 1F, the data agent 142 forms the datastream 170 from the data associated with a client computing device 102(e.g., primary data 112). The data stream 170 is composed of multiplepairs of stream header 172 and stream data (or stream payload) 174. Thedata streams 170 and 171 shown in the illustrated example are for asingle-instanced storage operation, and a stream payload 174 thereforemay include both single-instance (“SI”) data and/or non-SI data. Astream header 172 includes metadata about the stream payload 174. Thismetadata may include, for example, a length of the stream payload 174,an indication of whether the stream payload 174 is encrypted, anindication of whether the stream payload 174 is compressed, an archivefile identifier (ID), an indication of whether the stream payload 174 issingle instanceable, and an indication of whether the stream payload 174is a start of a block of data.

Referring to FIG. 1G, the data stream 171 has the stream header 172 andstream payload 174 aligned into multiple data blocks. In this example,the data blocks are of size 64 KB. The first two stream header 172 andstream payload 174 pairs comprise a first data block of size 64 KB. Thefirst stream header 172 indicates that the length of the succeedingstream payload 174 is 63 KB and that it is the start of a data block.The next stream header 172 indicates that the succeeding stream payload174 has a length of 1 KB and that it is not the start of a new datablock. Immediately following stream payload 174 is a pair comprising anidentifier header 176 and identifier data 178. The identifier header 176includes an indication that the succeeding identifier data 178 includesthe identifier for the immediately previous data block. The identifierdata 178 includes the identifier that the data agent 142 generated forthe data block. The data stream 171 also includes other stream header172 and stream payload 174 pairs, which may be for SI data and/or fornon-SI data.

FIG. 1H is a diagram illustrating the data structures 180 that may beused to store blocks of SI data and non-SI data on the storage device(e.g., secondary storage device 108). According to certain embodiments,the data structures 180 do not form part of a native file system of thestorage device. The data structures 180 include one or more volumefolders 182, one or more chunk folders 184/185 within the volume folder182, and multiple files within the chunk folder 184. Each chunk folder184/185 includes a metadata file 186/187, a metadata index file 188/189,one or more container files 190/191/193, and a container index file192/194. The metadata file 186/187 stores non-SI data blocks as well aslinks to SI data blocks stored in container files. The metadata indexfile 188/189 stores an index to the data in the metadata file 186/187.The container files 190/191/193 store SI data blocks. The containerindex file 192/194 stores an index to the container files 190/191/193.Among other things, the container index file 192/194 stores anindication of whether a corresponding block in a container file190/191/193 is referred to by a link in a metadata file 186/187. Forexample, data block B2 in the container file 190 is referred to by alink in the metadata file 187 in the chunk folder 185. Accordingly, thecorresponding index entry in the container index file 192 indicates thatthe data block B2 in the container file 190 is referred to. As anotherexample, data block B1 in the container file 191 is referred to by alink in the metadata file 187, and so the corresponding index entry inthe container index file 192 indicates that this data block is referredto.

As an example, the data structures 180 illustrated in FIG. 1H may havebeen created as a result of two storage operations involving two clientcomputing devices 102. For example, a first storage operation on a firstclient computing device 102 could result in the creation of the firstchunk folder 184, and a second storage operation on a second clientcomputing device 102 could result in the creation of the second chunkfolder 185. The container files 190/191 in the first chunk folder 184would contain the blocks of SI data of the first client computing device102. If the two client computing devices 102 have substantially similardata, the second storage operation on the data of the second clientcomputing device 102 would result in the media agent 144 storingprimarily links to the data blocks of the first client computing device102 that are already stored in the container files 190/191. Accordingly,while a first storage operation may result in storing nearly all of thedata subject to the storage operation, subsequent storage operationsinvolving similar data may result in substantial data storage spacesavings, because links to already stored data blocks can be storedinstead of additional instances of data blocks.

If the operating system of the secondary storage computing device 106 onwhich the media agent 144 operates supports sparse files, then when themedia agent 144 creates container files 190/191/193, it can create themas sparse files. A sparse file is type of file that may include emptyspace (e.g., a sparse file may have real data within it, such as at thebeginning of the file and/or at the end of the file, but may also haveempty space in it that is not storing actual data, such as a contiguousrange of bytes all having a value of zero). Having the container files190/191/193 be sparse files allows the media agent 144 to free up spacein the container files 190/191/193 when blocks of data in the containerfiles 190/191/193 no longer need to be stored on the storage devices. Insome examples, the media agent 144 creates a new container file190/191/193 when a container file 190/191/193 either includes 100 blocksof data or when the size of the container file 190 exceeds 50 MB. Inother examples, the media agent 144 creates a new container file190/191/193 when a container file 190/191/193 satisfies other criteria(e.g., it contains from approximately 100 to approximately 1000 blocksor when its size exceeds approximately 50 MB to 1 GB).

In some cases, a file on which a storage operation is performed maycomprise a large number of data blocks. For example, a 100 MB file maycomprise 400 data blocks of size 256 KB. If such a file is to be stored,its data blocks may span more than one container file, or even more thanone chunk folder. As another example, a database file of 20 GB maycomprise over 40,000 data blocks of size 512 KB. If such a database fileis to be stored, its data blocks will likely span multiple containerfiles, multiple chunk folders, and potentially multiple volume folders.Restoring such files may require accessing multiple container files,chunk folders, and/or volume folders to obtain the requisite datablocks.

Example Information Management Systems Including Local DeduplicationDatabase(s)

Examples of systems and methods will now be described for usinginformation local to a secondary storage computing device 106 to improveinformation management operations, particularly with respect tomanagement of a stored set of deduplicated data. For example,deduplication data block information can be updated on a generallycontinuous or otherwise frequent basis in memory that is local to one ormore secondary storage computing devices 106. These local updates can beforwarded for persistent storage in one or more secondary storagedevice(s) 108 according to a transaction-based scheme, thereby providinga relatively robust and efficient mechanism for maintainingdeduplication information in the secondary storage subsystem 118.

While described in some cases with respect to certain types ofoperations (e.g., backup and pruning operations), the techniquesdescribed herein may be equally compatible with other types of storageoperations including archive, snapshot, and replication operations, toname a few. Descriptions of embodiments of these and other types storageoperations compatible with embodiments described are provided above.Moreover, certain aspects of such techniques may be employed for use inconjunction with stored data sets that are not deduplicated.

FIG. 2 shows a block diagram illustrative of an embodiment of aninformation management system 100. In the illustrated embodiment of FIG.2, the information management system 100 further includes one or morelocal databases 202A, 202B (referred to together as local database(s)202), an event log 204, one or more secondary storage devices 108 acontaining a deduplication database 206 that includes a set of entriesassociated with a set of data blocks 207, and one or more storagedevices 108 b containing the set of data blocks 207 themselves. Thededuplication database 206 and the set of data blocks 207 can togetherform a deduplicated data store, where the set of data blocks 207 formconstituent parts of a set of files represented by the deduplicated datastore. For instance, the data blocks in the set of data blocks 207 arededuplicated according to a deduplication scheme and each entry in thededuplication database 206 can include a signature of the respectivedata block (e.g., a hash of the data block) and a reference countcorresponding to a number of instances of the respective data block thatexist in the set of files represented by the deduplicated data store.

For purposes of the example, the illustrated embodiment has beensimplified to include two client computing devices 102, a single storagemanager 140, a single secondary storage computing device 106 andcorresponding media agent 144, and two secondary storage device 108 a,108 b. In other embodiments, different numbers of components arepossible. For instance, any desired number of client computing devices102, secondary storage computing devices 106, media agents 144, andsecondary storage devices 108 may be employed, depending on theembodiment.

The deduplication database 206 in the illustrated embodiment isimplemented in one or more storage devices 108 a that are separate anddistinct from the secondary storage computing devices 106. For instance,the deduplication database 206 can communicate with the other componentsof the information management system 100 via a network such as a SAN,LAN, and/or WAN. In certain other embodiments, the deduplicationdatabase 206 can be located at another location. For instance, thededuplication database 206 in one embodiment is contained in one normore media agent databases 152 associated with the secondary storagecomputing device(s) 106 (not shown in FIG. 2; see, e.g., FIGS. 1C-1E).In such embodiments, the deduplication database 206 can communicate withthe secondary storage computing device 106 via a communication bus, suchas via SCSI connection.

In some embodiments, the system 100 can include multiple deduplicationdatabases 206, such as one for each secondary storage computing device106, and/or can include only one deduplication database 206 that isshared amongst multiple secondary storage computing devices 106 andcorresponding media agents 144. When multiple deduplication databases206 are used, a storage policy can determine the allocation of thededuplication information amongst the multiple deduplication databases,e.g., based on a scheme using data block signatures, as described ingreater detail in U.S. Pat. Pub. No. 2012/0150826, previouslyincorporated herein by reference. In some embodiments, the deduplicationdatabase 206 resides on a slower storage medium than the local database202. For example, if the local database 202 is implemented in the mainmemory of the secondary storage computing device 106, the deduplicationdatabase 206 can be implemented as an on-disk database, such as on ahard drive, disk drive, solid-state drive or other storage medium. Forinstance, the deduplication database 206 according to some embodimentsis implemented in persistent and/or non-volatile memory, where thecontents of the deduplication database 206 are persistently stored andremain accessible in the event of a power down of the memory on whichthe deduplication database 206 resides, or in the event of a crash orother failure associated with the secondary storage computing device106.

As shown, the deduplication database 206 is stored separately from thecorresponding set of data blocks 207. This architecture can providecertain advantages including enhanced scalability, as is described inmore detail in U.S. Pat. Pub. No. 2012/0150826. In some embodimentsincluding the illustrated embodiment, the deduplication database 206stores database entries that correspond to a set of data blocks 207contained in the one or more secondary storage devices 108 b. Forexample, the database entries in the deduplication database 206 caninclude or be referred to as signature blocks, where each signatureblock corresponds to a deduplication data block that is stored in theone or more secondary storage devices 108 b. The signature blocks caninclude a hash or other deduplication signature of the correspondingdata block (also referred to as a data block signature), as well asadditional information, such as the location (e.g., memory deviceidentifier and/or memory address) of the data block, the number ofreferences to the data block in the deduplicated data store (alsoreferred to as a reference count), the location (e.g., memory deviceidentifier and/or memory address) of references (e.g., pointers) to thedata block within the secondary storage device(s) 108 b, and/or the ageof each reference, etc., as described in greater detail below withreference to FIGS. 3A and 3B and in U.S. Patent App. Pub. No.2013/0346373, entitled Collaborative Restore in a Networked StorageSystem, which is hereby incorporated herein by reference in itsentirety.

As data blocks are added to and/or removed from the secondary storagedevice(s) 108 b, the signature blocks in the deduplication database 206can be created, modified, and/or deleted as appropriate, as described ingreater detail below. In addition, according to a storage policy, thededuplication database 206 can be backed up to secondary storage in theevent of a deduplication database 206 failure, for subsequent restore.

The secondary storage computing device 106 can advantageously locallystore and maintain information associated with the deduplication datastore. Such information can include information corresponding to entriesin the deduplication database 206. For instance, in the illustratedembodiment, the secondary storage computing device 106 maintains localdatabases 202A, 202B. The local databases 202A, 202B can be organized ina database format or in any other appropriate data structure or format,depending on the embodiment. As is discussed herein, such locallymaintained information can be useful in a transaction-based scheme toflush updates to the deduplication database 206.

The local database 202 can store working copies of database entries(e.g., signature blocks) that are, or will be, stored in thededuplication database 206. In some embodiments, the local database 202stores a subset of the database entries stored in the deduplicationdatabase 206. For instance, as will be discussed in further detail, thelocal database 202 can store working copies corresponding to a subset ofthe database entries that have been recently modified. In certain otherembodiments, local database 202 stores working copies of all of thedatabase entries stored in the deduplication database 206. In someembodiments, the local database 202 can be implemented in main memory ofthe secondary storage computing device 106. For example, the localdatabase 202 can be implemented in RAM of the secondary storagecomputing device 106. For instance, the local database 202 can beimplemented in relatively faster memory than the memory on which thededuplication database 206 is stored. The local database 202 can bestored in non-persistent and/or volatile memory, e.g., where thecontents of the local database 202 may be lost in the event of a powerdown of the memory on which the local database 202 resides, or in theevent of a crash or other failure associated with the secondary storagecomputing device 106. In certain other embodiments, the local database202 can be implemented in longer term storage, such as a hard drive,disk drive, solid-state drive, etc.

Each of the working copies of the database entries generally includesinformation about a corresponding data block in the set of data blocks207, and can include, for example, information included in thecorresponding database entry in the deduplication database 206. Forinstance, the working copy can include a complete copy of thecorresponding signature blocks in the deduplication database 206, or anyportion thereof. In certain embodiments, each working copy includes adata block signature and a reference count associated with thecorresponding data block. The reference count can indicate the number ofreferences to the data block in the set of files represented by thededuplicated data store. In certain embodiments, each working copy caninclude other information associated with the corresponding data block,such as the storage location of the data block (e.g., memory deviceidentifier and memory address) and/or other information from thecorresponding signature data block stored in the deduplication database206.

Depending on the situation, the working copies in the local database 202can be derived from database entries obtained from the deduplicationdatabase 206 and/or from deduplication information that does not yetexist in the deduplication database 206 but is instead newly received,e.g., as part of an on-going backup or other information managementoperation. For example, as will be described in further detail, e.g.,with reference to FIG. 4, as part of a backup operation in which data isbeing backed up from the primary storage devices 104 to the deduplicateddata store in secondary storage devices 108 a, 108 b, it may beappropriate to create and/or modify database entries in thededuplication database 206 that correspond to data blocks that form thefiles in the backup data set. As the secondary storage computing device106 processes the backup data set, it can identify the data blocks andcan query the local database 202 for working copies of the databaseentries corresponding to those data blocks. Where working copies exist,the secondary storage computing device 106 can modify the working copyas appropriate. Where working copies do not exist, the secondary storagecomputing device 106 can request the appropriate database entry from thededuplication database 206, such as where the data block already existsin the deduplicated data store. Or the secondary storage computingdevice 106 can create a new database entry, such as where a newly addeddata block is entering the deduplicated data store as part of the backupoperation. Once a working copy of a database entry is obtained, thesecondary storage computing device 106 updates the working copy asappropriate. For instance, any of the following types of updates arepossible, without limitation:

-   -   incrementing a reference count of the database entry, such as        where one or more new instances of existing data block are added        to the deduplicated data store;    -   decrementing a reference count of the database entry, such as        where one or more instances of the existing data block are        deleted from the deduplicated data store; and    -   adding an indication to the database entry that the        corresponding data block is to be pruned/deleted, such as where        there are no remaining instances of the data block referred to        in the deduplicated data store, e.g., in the case of a pruning        or archive operation.

Thus, the local database can operate similar to a cache where therelevant working copy is already found in the local database 202, and itcan be modified as appropriate. On the other hand, if the working copyis not found in the local database 202, it is either generated by thesecondary storage computing device 106 or received from thededuplication database 206. For example, the secondary storage computingdevice 106 can query the deduplication database 206 for thecorresponding entry. If the deduplication database 206 has the databaseentry, it can send the entry or a portion thereof to the secondarystorage computing device 106 for storage in the local database 202 as aworking copy. If the deduplication database 206 does not have the entry,the local database 202 can generate the entry locally as a working copy.The working copy can include, but is not limited to, the data blocksignature, information relating to the location of the data block insecondary storage, and a count corresponding to the number of referencesto the data block that exist in the files maintained in the deduplicateddata store.

As indicated, the working copies in the local database 202 can be mergedwith the deduplication database 206 in order to update the informationin the deduplication database 206. For example, the working copies canbe merged once a threshold number of working copies reside in the localdatabase 202. In some embodiments, the working copies can be merged oncethe local database 202 reaches a threshold size (e.g., 10 MB, 100 MB, 1GB, etc.). In certain embodiments, the working copies can be merged withthe deduplication database entries once a threshold time period has beenreached, e.g., since the last merge operation. The threshold time can bemeasured since a previous merge and/or other event, and can be anyappropriate value depending on the embodiment, such as least 10 seconds,at least 20 seconds, at least 30 seconds, at least 1 minute, at least 2minutes, at least 5 minutes, or at least 10 minutes, or more. During orafter a merge operation, the local database 202 or a portion thereof canalso be flushed to free up space. For example, during a flush, some orall of the working copies can be deleted from one or more of the localdatabases 202A, 202B.

As illustrated in FIG. 2, the secondary storage computing device 106 caninclude multiple local databases, such as local databases 202A, 202B. Insome other cases, only one local database 202A is used. Although theillustrated embodiment of FIG. 2 only shows two local databases 202A,202B, it will be understood that the secondary storage computing device106 can include more than two local databases, as desired. When multiplelocal databases 202 are used, the local databases 202 can bedaisy-chained together, such that if one local database (e.g., 202B)does not have a working copy of a particular database entry, thesecondary storage computing device 106 can query one or more other localdatabases (202A, etc.) for the working copy before requesting thedatabase entry from the deduplication database 206.

For example, in some embodiments, once a first local database (202A)begins to merge with the deduplication database 206, it can be placed inread-only mode (e.g., the information management system 100 can removewrite-access) and a second local database (202B) can be identified asthe active local database and begin storing and modifying working copiesof the database entries. The working copies in the second local database202B can be obtained or derived from database entries received from thefirst (or read-only) local database 202A, or other local databases 202if present, the deduplication database 206.

For example, with reference to FIG. 2, when a working copy of aparticular a database entry to be modified does not already reside inthe second local database 202B, the secondary storage computing device106 can query the first local database 202A for a copy. If the firstlocal database 202A has a copy of the database entry in question, thesecondary storage computing device 106 can store it in the second localdatabase 202B as a working copy and modify it as appropriate. If thefirst local database 202A does not have the database entry, thesecondary storage computing device 106 can query the deduplicationdatabase 206 for the database entry. If the deduplication database 206has the database entry, it can send it to the secondary storagecomputing device 106 for storage in the second local database 202B asthe working copy, for modification as appropriate. If the deduplicationdatabase 206 does not have a database entry corresponding to the datablock in question, the data block is new to the deduplicated data store.Thus, the secondary storage device 106 can compile a working copy usingthe information provided to it as part of the information managementoperation (e.g., backup) that involves the data block, for storage inthe second local database 202B.

The event log 204 can be a data structure used to track storage eventsassociated with the deduplicated data store. The event log 204 canreside on a storage device that is separate and distinct from thesecondary storage computing device 106 and/or can reside on memoryassociated with the secondary storage computing device 106, such as partof the media agent database 152. The secondary storage computing device106 may create and/or maintain the event log 204, for example. Incertain embodiments, each local database 202A, 202B can be associatedwith a separate event log 204, or a single event log may separatelygroup entries associated with each local database 202A, 202B. In someembodiments, the event log 204 is maintained persistently innon-volatile storage, such that the event log 204 is available for usein recovery operations in the event of a crash of the secondary storagecomputing device 106 or its corresponding media agent 144, as will bediscussed further herein.

Log entries associated with relevant storage events can be added to theevent log 204, either as the events occur, or following completion ofthe events. For example, during an information management operation,such as a backup operation, snapshot operation, etc., each modificationto a working copy of the local database 202 can be stored in the eventlog 204. The event log 204 can include information such as which workingcopy was modified, how it was modified (e.g., database entry added fornew data block, reference count incremented/decremented, etc.), atimestamp, etc. In some cases, the event log 204 does not log or trackpruning events, or events that result or are intended to result in thedeletion of a data block from the set of data blocks 207 and/or acorresponding database entry from the deduplication database 206. Forinstance, where an storage event results in the reference count of aworking copy in the local database 202 decrementing to zero, indicatinga deletion of the corresponding data block and/or data base entry isappropriate, the event log 204 in some cases does not add acorresponding log entry. In contrast, the event log 204 in such casescan be configured to add a log entry for a storage even resulting in theaddition of a data block to the set of data blocks 207, or a storageevent resulting in the incrementing of the reference count of a workingcopy in the local database 202.

Additional information related to the information management operationcan be included in the event log 204 as appropriate, such as thestart/end time of an operation on the primary storage subsystem 117and/or deduplication database 206, start/end time of a merge operationbetween the local database 202 and the deduplication database 206,timestamp indicating when a working copy was generated or pruned, etc.In embodiments where each local database 202A, 202B has a correspondingevent log 204, the event log 204 for each local database 202A, 202B canstore log entries of the storage events that occurred when thecorresponding local database 202A, 202B was active.

In some embodiments, the event log 204 can be pruned, flushed orotherwise modified over time. For example, following a merge of thelocal database 202 with the deduplication database 206, the log entriesin the event log 204 that correspond to the working copies that weremerged with the deduplication database 206 can be deleted, or the entireevent log can be flushed. Similarly, following a backup of thededuplication database 206 to the secondary storage device 108, the logentries that correspond to the database entries in the deduplicationdatabase 206 that were backed up to the secondary storage device 106 canbe deleted in some cases.

The information stored by the event log 204 can be used by theinformation management system 100 to restore the local database 202following the unavailability or failure of the secondary storagecomputing device 106, as described in greater detail below, e.g., withreference to FIG. 8. For example, following a secondary storagecomputing device 106 failure, the information management system 100 canuse the event log 204 to identify the most recent merge time of thelocal database 202 with the deduplication database 206. In addition, theinformation management system 100 can identify the storage events forwhich entries (e.g., working copies) in the local database 202 were notmerged with the corresponding entries in the deduplication database 206as a result of the secondary storage computing device 106 failure (e.g.,the storage events that occurred after the merge time). Once identified,the information management system 100 can replay the storage events thatwere not merged to recreate, or reconstruct, the entries (e.g., workingcopies) in the local database 202. Once the entries in the localdatabase 202 are reconstructed, they can be merged with thededuplication database 206. Following the merge, the storage manager 140can indicate that the deduplication database 206 is up-to-date, oronline.

Example Deduplication Database

FIG. 3A is a block diagram illustrative of an expanded view of anembodiment of the deduplication database 206, which can be implementedon one or more storage devices. Although not illustrated in FIGS. 3A and3B, one or more computing devices and/or software modules (e.g., one ormore secondary storage computing devices 106 and/or corresponding mediaagents 144) can maintain and convey data to and from the deduplicationdatabase 206.

While the data block-related information in the deduplication database206 can be organized in a variety of ways, in certain embodiments, theinformation is arranged as a plurality of signature blocks 306 as shownin FIG. 3A. Each signature block 306 can correspond to a unique orsubstantially unique data block signature 308 and corresponding datablock in the deduplicated data store.

In some embodiments, each signature block 306 includes informationregarding the references stored in the deduplicated data store in thesecondary storage subsystem 118 that refer to the corresponding datablock (also referred to as data block references). Furthermore,signature blocks 306 stored in the deduplication database 206 caninclude various other pieces of information, or metadata associated withthe corresponding data block. For example, each signature block 306 caninclude a signature field 308 including the data block signature 308, anumber of references (or reference count) field 310 that identifies thenumber references to the data block that are found in the deduplicateddata store in the secondary storage subsystem 118, a data block locationfield 312 that provides the storage location of the data block in thesecondary storage subsystem 118 (e.g., memory device identifier andmemory address information). The signature block 306 can also include aset of reference entries 314, each corresponding to a differentreference to the data block in the deduplicated data store. As oneillustrative example, three files are stored in the deduplicated datastore. Two instances of a particular data block form constituent partsof the first file, a single instance of the data block is included inthe second file, and the third file does not include any instances ofthe data block. In this example, there would be three reference entries314 corresponding to the three instances of that data block. Thereference entries 314 can further include a location information field318 and an age information field 322, described further below.

Each signature block 306 can include additional or less information asdesired. Moreover, in some embodiments, the deduplication database 206can be organized differently. For instance, while the illustratedembodiment generally groups entries for the data block references into aseparate signature block 306 for each unique signature; otherembodiments may instead organize the entries according to some otherscheme. In some embodiments, entries can be grouped based on the timethe data block reference was added to the secondary storage subsystem118, or according to any other appropriate scheme.

Generally speaking, the data block signatures 308 can be used as areference to determine whether a particular data block is already storedin the secondary storage subsystem 118 and/or in the local database 202or deduplication database 206. The signature in the signature field 308can be derived by performing a hash or other function on thecorresponding data block. The signature 308 can be generated by avariety of different components, depending on the implementation, suchas the client computing device 102, the secondary storage computingdevice 106, the storage manager 140, the media agent 144, and/or amodule executing on a primary storage device 104 or secondary storagedevice 108. In some embodiments, signatures 308 are derived each timedata is written to or modified on a primary storage device 104. In othercases, signatures 308 are generated in association with a backup,restore, or other storage operation, or based on some other appropriateschedule, as determined by the storage policy. In an embodiment, theSHA-512 algorithm is used (e.g., on a 64 kB or 128 kB data block) toderive the signature 308. In some embodiments, the resulting signatureis 256 bytes, and can be used for deduplication purposes. Hash functionsother than SHA-512 can be used on the data blocks to derive thesignature, as well as other non-hash functions. In addition, differentsized signatures may be used.

The data block location field 312 can indicate the location of the datablock in the secondary storage subsystem 118. The location informationcan include physical and/or logical memory address information usable toaccess the data block within the secondary storage device(s) 108. Forexample, the location information can include, but is not limited to, anidentifier of the memory device or other information store where thedata block resides, a cluster identifier and/or an offset.

FIG. 3B is a block diagram illustrative of an expanded view of anexample of an entry 314 of a signature block 306 from FIG. 3A. In theillustrated example, each entry includes a reference ID field 316, alocation information field 318, an access/priority information field330, and an age information field 322.

The reference ID field 316 can include an identifier for a particulardata block reference stored in the secondary storage subsystem 118. Forexample, in some embodiments, the first reference to the data block canhave a reference ID of one, the second reference to the data block canhave a reference ID of two, etc.

The location information field 318 can include information specifyingthe location of the data block reference in the secondary storagesubsystem 118. The location information can additionally includephysical and/or logical memory address information usable to access thereference to the data block within the secondary storage device 108. Forexample, the location information can include, but is not limited to, anidentifier for the information store (e.g., memory device identifier)where the data block resides, a cluster identifier and/or an offset.

Each reference entry 314 can also include age information in an agefield 322. The age field 322 can be used to determine how long aparticular reference to a data block has existed in the secondarystorage subsystem 118. The age field 322 in one embodiment includes anage ID which can be an alphanumeric indication of when the referenceentry 314 was added or revised relative to other reference entries. Forinstance, the age ID may be a unique identifier for the particularreference to the data block.

The signature block 306 and/or corresponding reference entries 314 cancontain fewer or more pieces of information than what is illustrated inthe examples shown in FIGS. 3A and 3B. For example, the signature block306 can include date data, such as the date when the signature block 306was created or modified, etc. In some embodiments, the reference entries314 can include file identifiers that indicate to which file, or backup,a reference entry 314 belongs. The file identifiers can be located inthe location field 318, in another field, or in a separate field.Furthermore, the reference entries 314 can include organizational datathat indicates where the data block corresponding to the reference entry314 is located with respect to other data blocks in a particular file,etc. In some embodiments, the signature block 306 and each referenceentry 314 can include a removal flag that indicates that the particularsignature block 306 and/or reference entry 314 can be removed as part ofa pruning operation, discussed in greater detail below with reference toFIGS. 6 and 7.

It will be understood, that although reference is made to thededuplication database 206, the embodiments described above can alsoapply to the local database 202, which includes complete or partialcopies of the database entries in the deduplication database 206.Furthermore, it will be understood that because the working copies ofthe database entries in the local database 202 include some or all ofthe information in a signature block 306, the embodiments describedabove with reference to the signature block 306 can also apply to theworking copies of the database entries in the local database 202.

Merging Local Database(s) with a Deduplication Database

FIG. 4 is a data flow diagram illustrative of an embodiment of theinteraction between the various components of the information managementsystem 100 of FIG. 2 with respect to a merge operation, where workingcopies of database entries in one or more local databases 202 are mergedwith the deduplication database 206. In this manner, deduplication datablock information can be updated on a generally continuous or otherwisefrequent basis local to the secondary storage computing device 106.These local updates can be forwarded for persistent storage in thesecondary storage device(s) 108 according to a transaction-based scheme,thereby providing a relatively robust and efficient mechanism formaintaining deduplication information in the secondary storage subsystem118.

Prior to performing a merge operation, the secondary storage computingdevice 106 can receive one or more instructions and/or data. Theinstructions can be to perform one or more information managementoperations, such as a backup or archive operation, deduplication datastore pruning operation, etc. As illustrated, the secondary storagecomputing device 106 can receive the instructions and/or data from thestorage manager 140 and/or the client computing devices 102. Forexample, as part of a (1A) backup operation, the secondary storagecomputing device 106 can receive data from the client computing devices102, as packaged by the appropriate corresponding data agents 142, forbackup to the secondary storage subsystem 118. The data can include oneor more files to be backed up to the secondary storage subsystem 118,for example. The secondary storage computing device 106 or otherappropriate entity in the secondary storage subsystem 118 can break thereceived files up at a level of chosen granularity into deduplicationdata blocks. In other cases, the data agent 142 or other appropriateentity in the primary storage subsystem 117 breaks the files up into thededuplication data blocks before sending the data to the secondarystorage computing device 106. The received data can also includededuplication signatures corresponding to the data blocks in some suchcases, or any other appropriate type of information.

Other types of operations are possible. As another example, the storagemanager 140 can instruct the secondary storage computing device 106 to(1B) prune the deduplication database 206 and/or set of data blocks 207.For example, the storage manager 140 can instruct the secondary storagecomputing device 106 to (1B) prune the deduplication database 206 and/orset of data blocks 207 as part of routine maintenance of thededuplication data store, or the pruning may result from anotherinformation management operation such as an archive operation.

The storage operation can be scheduled based on any desired storagepolicy indicating that at certain times (e.g., once a day, once a week,etc.) or following certain events a particular storage operation is tobe performed.

The secondary storage computing device 106 (2A) processes theinstructions and/or data and (2B) logs the storage events as they occurinto the event log 204. As part of the processing, the secondary storagecomputing device 106 can determine what changes to the deduplicationdatabase 206 and/or set of data blocks 207 are appropriate. For example,the secondary storage computing device 106 can determine whether entriesare to be added, removed, or modified (e.g., reference countsincremented or decremented) from the deduplication database 206.Furthermore, in some embodiments, as part of the processing, thesecondary storage computing device 106 can generate entries (e.g.,including data block signatures and other appropriate information) thatcorrespond to data blocks that are (or will be) stored in the set ofdata blocks 207.

In addition, as part of the processing, the secondary storage computingdevice 106 can determine whether any of the working copies of databaseentries that are already stored in the local databases 202 are affectedby the storage operations. For example, the secondary storage computingdevice 106 can query the local database (e.g., local database 202A) forsignatures that are part of the storage operation. If the secondarystorage computing device 106 determines that the active local database202A includes the relevant working copies, it can omit step (3).

As part of logging the events (2B), the secondary storage computingdevice 106 can log what storage events and/or associated modificationsto the working copies in the local database 202 occurred, the time theyoccurred, and information regarding the other storage events as theyoccur, etc. It is to be understood that the secondary storage computingdevice 106 can log the storage events at any appropriate time, e.g.,before, after, or concurrently with, any one of the actions illustratedin FIG. 4.

Upon processing the instructions, the secondary storage computing device106 can (3) request and receive relevant data from the deduplicationdatabase 206. For example, if the secondary storage computing device 106determines that a working copy of an entry corresponding to a particulardata block is not found in the local database 202, it can request theparticular entry, and/or any other relevant information, from thededuplication database 206. The requested entry and other informationcan include, but is not limited to, the data block signature, referencecount of the signature, the location of the corresponding data block,etc.

The secondary storage computing device 106 (4) modifies the localdatabase 202 as appropriate, in accordance with the data received fromthe client computing devices 102 (1A) and/or the storage manager 140(1B). For example, if the files to be backed up include one or morereferences to a data block that already exists in the set of data blocks207 of the deduplicated data store, the secondary storage computingdevice 106 can increment the reference count of the working copy of thecorresponding database entry. On the other hand, if a file is beingmodified or deleted such that one or more references to a data blockthat already exists in the set of data blocks 207 are to be deleted, thesecondary storage computing device 106 can decrement the reference countof the working copy of the corresponding database entry. Upondecrementing the reference count, the secondary storage computing device106 can also determine whether any references to the data block remainwithin the secondary storage device 108. For example, if the referencecount is decremented to less than a threshold count, such as one, thesecondary storage computing device 106 can determine that thecorresponding data block is no longer needed and should be pruned fromthe set of data blocks 207. Accordingly, the secondary storage computingdevice 106 can modify the working copy of the database entry to includeinformation sufficient to indicate that the corresponding database entryshould be removed from the deduplication database 206 and/or that thedata block should be removed from the set of data blocks 207.

If after processing the instructions, the secondary storage computingdevice 106 determines that the backup data set includes a new data blockthat does not already exist in the set of data blocks 207, the secondarystorage computing device 106 can create a working copy of the databaseentry. Accordingly, in some instances, the local database 202 caninclude working copies of newly generated database entries that are notfound in the deduplication database 206. The secondary storage device106 may process the data block to generate the data block signature, forexample, and then compile the working copy by including the generatedsignature as well as a reference count of one, or of greater than one ifthere are plural instances of the data block in the set of files to bebacked up.

According to a storage policy, the secondary storage computing device106 can (5) merge the local database 202 with the deduplication database206. As part of the merge, the secondary storage computing device 106can modify the local database 202 to be read-only such that noadditional modifications can be made to the local database 202 duringthe merge. This can help keep the local database 202 and thededuplication database 206 synchronized. In this way, the informationmanagement system 100 can act as a transaction-based system.

In addition, as part of the merge operation, the secondary storagecomputing device 106 can send working copies of the database entriesthat are stored in the local database 202 to the deduplication database206. The deduplication database 206 can update the deduplicationdatabase 206 based on the received working copies, e.g., by comparingthe working copies of the database entries with the database entriesthat reside in the deduplication database 206 and make changesaccordingly.

For example, if a database entry corresponding to the working copy inthe local database 202 does not exist in the deduplication database 206,the deduplication database 206 can generate a new database entry basedon the received working copy. If the working copy received from thesecondary storage computing device 106 indicates that additionalreferences to a data block have been, or will be, added to the secondarystorage device 108, the deduplication database 206 can update thecorresponding signature block with the relevant information. For examplethe deduplication database 206 can increment the reference count of thesignature block and/or include the location of the new reference to thesignature block within the secondary storage device 108.

Similarly, if the working copy received from the secondary storagecomputing device 106 indicates that one or more references to a datablock are to be removed from the secondary storage device 108, thededuplication database 206 can update the corresponding signature block(or other type of entry in the deduplication database 206) with therelevant information. For example, the deduplication database 206 candecrement the reference count of the signature block and indicate thelocation within the secondary storage devices 108 a, 108 b, where thecorresponding reference to the data block resides.

It will be understood that for simplicity, only some of the operationsperformed by the different components are illustrated. For example, inaddition to what is illustrated in FIG. 4 and described below, thesecondary storage computing device 106 can perform a number of otheroperations before, after, or concurrently with the operations describedbelow. In addition, the deduplication database 206 and/or the set ofdata blocks 207 can be (6) backed up to one or more other secondarystorage devices (not shown) according to a storage policy. In someembodiments, the backup of the deduplication database 206 and/or the setof data blocks 207 is handled by the secondary storage computing device106.

Furthermore, although not illustrated in FIG. 4, it will be understoodthat the information management system 100 can perform additionaloperations. For example, in some embodiments, when one local database202A is merging with the deduplication database 206, that local database202A can be set to read-only, and a second local database 202B becomesthe active local database. Accordingly, modifications to working copiesare made in the second local database 202B during the merge. In certainembodiments, once the merge is completed, the working copies residingwithin the merged local database 202 are deleted. In some embodiments,following the merge, the log entries in the event log 204, or the entireevent log 204, that correspond to the merged local database 202A aredeleted. In some cases, more than two local databases 202A, 202B can beemployed. For instance, where both the first and second local databases202A, 202B become full or are otherwise scheduled for merging with thededuplication database 206, but have not yet been merged, the first andsecond local databases 202A, 202B can be designated as inactive pendingthe merge (e.g., set to read only permission), and a third localdatabase can be created as an active database. Any number of localdatabases can be created in this manner in some embodiments, therebyallowing the secondary storage computing device 106 to continueprocessing the backup or other information management operation whilethe merges of the inactive local databases 202 are pending. In someother cases, there is a pre-defined maximum number of local databases202A, 202B that can be created. Once the maximum is reached, one or moreof the inactive local databases 202 must be merged with thededuplication database 206 and/or flushed before further operationsinvolving the use of the local database 202 can proceed.

FIG. 5 is a flow diagram illustrative of an embodiment of a routine 500implemented by the information management system 100 to merge a localdatabase 202 with the deduplication database 206. One skilled in therelevant art will appreciate that the elements outlined for routine 500can be implemented by one or more computing devices/components that areassociated with the information management system 100, such as theclient computing device 102, data agent(s) 142, media agent(s) 144,secondary storage computing device 106, and/or storage manager 150.Accordingly, routine 500 has been logically associated as beinggenerally performed by information management system 100. However, thefollowing illustrative embodiment should not be construed as limiting.

At block 502, the system receives one or more instructions to modify adatabase entry in the deduplication database 206. As described ingreater detail above, the instructions can include one or moreinstructions to store or prune a data block in secondary storage,add/remove an entry in the deduplication database 206,increment/decrement the reference count of an entry, and the like. Inaddition, as described previously, the database entry in thededuplication database 206 can include a data block signature thatcorresponds to a data block that has resided, does reside, or willreside in the secondary storage device 108.

At decision block 504, the information management system 100 determineswhether a working copy of the database entry resides in the localdatabase(s) 202. To determine whether the local database(s) 202 includesa working copy of the database entry, the information management system100 can query the local database(s) 202 for the data block signature. Ifthe data block signature is found in the local database(s) 202, theinformation management system 100 can move to block 508, discussedbelow.

However, if the information management system 100 determines that theworking copy is not in the local database, the information managementsystem 100 can query the deduplication database 206 for thecorresponding entry or to otherwise obtain the relevant data, asillustrated in block 506. If the deduplication database 206 has an entrycorresponding to the relevant data block (or includes the relevant datain some other appropriate form), it can return it to the secondarystorage computing device 106. If the deduplication database 206 does nothave an entry corresponding to the relevant data block (and does notinclude the relevant data in other form), it can inform the secondarystorage computing device 106 that this is the case.

In some embodiments, the relevant data queried for by the informationmanagement system 100 includes the database entry in the deduplicationdatabase 206 including the data block signature, or a portion thereof.In certain embodiments, upon receipt of the request from the secondarystorage computing device 106, the information management system 100 canreview the database entries for an entry that matches the data blocksignature. For example, another secondary storage computing device (notshown) associated with the secondary storage device 108 a may review theentries in the deduplication database 206. In some cases, the samesecondary storage computing device 106 that maintains the local database202 can perform the review. If the entry is found, the database entry(or portions thereof) can be sent to the secondary storage computingdevice 106. For example, the secondary storage computing device 106 canreceive the entry or a portion thereof, e.g., including the data blocksignature and the reference count of the signature obtained from thededuplication database 106. For instance, where another secondarystorage computing device performs the review, it can forward therelevant information to the secondary storage computing device 106 thatmaintains the local database 202. On the other hand, if the signature isnot found, an indication can be sent to the secondary storage computingdevice 106 indicating that the deduplication database 206 does notinclude an entry corresponding to the data block.

At block 508, the information management system 100 modifies the workingcopy of the database entry in the local database 202 based on thereceived instruction. In some embodiments, modifying the working copyincludes generating the working copy, editing the working copy, addinginformation to the working copy sufficient to indicate that thecorresponding data block and/or database entry are to be deleted, and/ordeleting the working copy. In certain embodiments, if the relevant datais not found in the deduplication database 206 indicating that the datablock is new to the deduplicated data store, and not already stored inthe set of data blocks 207, the secondary storage computing device 106can generate a working copy that can in turn be used as part of a mergeoperation to generate a database entry in the deduplication database206.

If the instructions indicate that a new reference to the data blockcorresponding to the signature is stored (or will be stored) in thededuplicated data store in the secondary storage subsystem 118, theinformation management system 100 can increment the reference count. Ifthe instructions indicate that a reference to the data blockcorresponding to the signature is being pruned from the deduplicateddata store in the secondary storage subsystem 118, the informationmanagement system 100 can decrement the reference count. Furthermore, ifthe information management system 100 determines that no more referencesto the data block corresponding to the signature reside (or will residefollowing the storage operation) in the secondary storage subsystem, theinformation management system 100 can indicate that the working copy,the database entry, and/or the corresponding data block should beremoved. In some embodiments, the information management system 100 canmake the indication by setting a flag in the working copy. In certainembodiments, the information management system 100 can make theindication by placing the working copy in a table including entries fordata blocks scheduled for deletion from the set of data blocks 207.

At block 510, the system merges the local database 202 with thededuplication database 206. In some embodiments, the informationmanagement system 100 merges the local database 202 with thededuplication database 206 according to a storage policy. As describedpreviously, in certain embodiments, the storage policy can indicate thatthe local database 202 is to merge with the deduplication database 206when a threshold time period has expired, e.g., since the last mergeoperation and/or when the size of the local database 202 satisfies athreshold size or contains a threshold number of entries/working copies.

As part of the merge operation, in some embodiments, the informationmanagement system 100 can compare the database entries in thededuplication database 206 with the working copies of the databaseentries that are stored in the local database 202. Based at least inpart on the comparison, the information management system 100 can updatethe database entries in the deduplication database 206.

For example, in some embodiments, if a database entry in thededuplication database 206 corresponding to a working copy in the localdatabase 202 cannot be found, the information management system 100 cangenerate the database entry. In certain embodiments, if the working copyin the local database 202 indicates that additional references to a datablock have been, or will be, added to the secondary storage device 108,the information management system 100 can update the correspondingsignature block in the deduplication database 206 with the relevantinformation. For example, the deduplication database 206 can incrementthe reference count of the signature block and/or include the locationof the new reference to the signature block within the secondary storagedevice 108.

Similarly, in some embodiments, if the working copy received from thesecondary storage computing device 106 indicates that one or morereferences to a data block are to be removed from the secondary storagedevice 108, the information management system 100 can update thecorresponding signature block in the deduplication database 206 with therelevant information. For example, the information management system 100can decrement the reference count of the signature block and indicatethe location within the secondary storage device 108, where thecorresponding reference resides. Furthermore, if the informationmanagement system 100 determines that there are no more references to aparticular data block, the information management system 100 can flagthe signature block and/or add an identifier for the data block (e.g.,the data block signature) to a table that can be used to remove the datablock from secondary storage.

Additional, fewer, or different blocks can be used to implement theroutine 500 without departing from the spirit and scope of thedescription. For example, when multiple local databases 202 are used,the active local database 202 can query one or more other localdatabases 202, such as one or more read-only local databases 202 for therelevant data prior to querying the deduplication database 206. If theone or more other local databases 202 include the relevant data, theinformation management system 100 can copy the data to the active localdatabase 202.

Pruning the Deduplication Data Store

FIG. 6 is a state diagram illustrative of an embodiment of theinteraction between the various components of the information managementsystem 100 with respect to a pruning operation where data blocks areremoved from the set of data blocks 207 and/or corresponding databaseentries are removed from the deduplication database 206. For example,and with reference again to FIG. 4, the secondary storage computingdevice 106 can (1B) receive an instruction to prune one or more datablocks from the set of data blocks 207 and/or one or more databaseentries from the deduplication database 206. This can be part of aroutine deduplication pruning operation directed by the storage manager,designed to free up space in the secondary storage subsystem 118. Or,the pruning can be a part of another information management operation.For instance, during an incremental backup operation some files in thebackup set may have been modified or deleted since the last backup, suchthat no files in the deduplicated data store include any instances ofsome subset of the data blocks in the set of data blocks 207. In suchcases, those data blocks can be scheduled for pruning. Pruning canadditionally be caused by an archive operation in which some data blocksare removed from the set of data blocks 207 and copied to one or moreother secondary storage devices, and thus scheduled for pruning.

As discussed, where a data block and/or database entry are to be pruned,the secondary storage computing device 106 can generally update theworking copy of the corresponding database entry to include informationsufficient to determine that the data block and/or database entry shouldbe deleted. For instance, the working copies of the correspondingdatabase entries in the local database 202 can be modified to decrementthe reference count to zero, set a pruning flag, or otherwise indicatethat deletion of the data block and/or corresponding database entry isappropriate.

With further reference to FIG. 4, as described previously, the changesto the local database 202 are (5) merged with the deduplication database206. Once merged, the deduplication database 206 can be reviewed by asecondary storage computing device, storage manager 140, or otherappropriate entity to identify the database entries and/or correspondingdata blocks that can be removed. For example, the deduplication database206 can generate a separate table of database entries and/orcorresponding data blocks scheduled for removal. In some embodiments, aflag can be set in association with the relevant database entriesidentifying the entries and/or the corresponding data blocks forremoval. Returning to FIG. 6, the secondary storage computing device 106can receive an instruction to (7) remove the data blocks from the set ofdata blocks 207 (and/or database entries from the deduplication database206) that have been scheduled for deletion/pruning. The secondarystorage computing device 106 can receive the instruction from thestorage manager 140 and/or initiate the removal based on a storagepolicy. In the illustrated embodiment, the secondary storage device 106that receives the instruction to perform the removal is the samesecondary storage device 106 that maintains the local database 202 andimplemented the merge with the deduplication database 206. In othercases, a different secondary storage computing device or otherappropriate entity performs the removal of the data blocks and/ordatabase entries scheduled for deletion.

The secondary storage computing device 106 (or another secondary storagecomputing device or other appropriate entity) can review thededuplication database 206 to identify database entries identified forremoval, e.g., as a result of one or more merge operations.

Once the secondary storage computing device 106 has identified the datablocks and/or corresponding database entries for removal, the secondarystorage computing device 106 can (9A/9B) remove them, or cause thesecondary storage devices 108 a, 108 b to remove them, as appropriate.Although not illustrated in FIG. 6, once completed, the deduplicationdatabase 206 can indicate to the secondary storage computing device 106,storage manager 140, or other appropriate entity that the removalprocess has completed successfully.

It will be understood that for simplicity, only some of the operationsperformed by the different components are illustrated. For example, inaddition to what is illustrated in FIG. 6, the secondary storagecomputing device 106 can perform a number of other operations before,after, or concurrently with the operations described below. For example,in addition to identifying the database entries and/or reference entries314 in the deduplication database 206 that are to be removed, thesecondary storage computing device 106 can identify the correspondingdata blocks (including data block references) in secondary storage thatare to be removed. The secondary storage computing device 106 can alsoinstruct the secondary storage device 108 to permanently remove thecorresponding data block reference and/or data block itself fromsecondary storage, as applicable.

FIG. 7 is a flow diagram illustrative of an embodiment of a routine 700implemented by the information management system 100 to prune thededuplication database 206. One skilled in the relevant art willappreciate that the elements outlined for routine 700 can be implementedby one or more computing devices/components that are associated with theinformation management system 100, such as the client computing device102, data agent(s) 142, media agent(s) 144, secondary storage computingdevice 106, deduplication database 206, and/or storage manager 150. Forinstance, the routine 700 can be implemented by the informationmanagement system 100 shown in any of FIGS. 2, 4, and 6. Accordingly,routine 700 has been logically associated as being generally performedby information management system 100. However, the followingillustrative embodiment should not be construed as limiting.

At block 702, the information management system 100 receives aninstruction to remove database entries to be pruned and/or correspondingdata blocks. For instance, in some embodiments, the instruction can bereceived from the storage manager 140. In certain embodiments, theinformation management system 100 initiates the removal process based ona storage policy. For example, the removal process can be initiatedfollowing one or more merge operations, once a day, once a week, etc.

At block 704, the information management system 100 queries thededuplication database 206 for database entries to be pruned. In someembodiments, the information management system 100 (e.g., a selectedsecondary storage computing device 106 or corresponding media agent 144)can review the database entries to identify the database entries and/orcorresponding data blocks to be pruned (e.g., entries that havesatisfied a threshold reference count). To accomplish this, in someembodiments, the information management system 100 can check a flag oneach database entry and/or each reference entry 314. In certainembodiments, the information management system 100 can check the actualreference count of each database entry. Furthermore, in someembodiments, as part of the merge operation, the information managementsystem 100 generates a separate table or other datastructure includingthe database entries and/or reference entries that are to be removed. Insuch embodiments the deduplication database 206 can identify thedatabase entries to be pruned based on the database entries found in thegenerated table. Once the database entries to be pruned are identified,the deduplication database 206 can send an identifier of the databaseentries to be pruned to the secondary storage computing device 106.

At block 706, the information management system 100 removes the datablocks scheduled for deletion from the set of data blocks 207 residingon the secondary storage devices 108 b. The information managementsystem 100 can use location information (e.g., memory device identifierand/or memory address information) present in the deduplication database206 to locate and remove the data blocks (including any data blockreferences). For instance, a secondary storage computing device 106 orother appropriate entity may access the location information from thedatabase entries in the deduplication database 206 that correspond toeach data block scheduled for deletion.

At block 708, the information management system 100 can in someembodiments remove at least a portion of the database entries scheduledfor deletion from the deduplication database 206. Such entries caninclude those that correspond to data blocks that were also deleted aspart of the pruning operation, for example, or that were previouslydeleted as part of another pruning operation.

Additional, fewer, or different blocks can be used to implement theroutine 700 without departing from the spirit and scope of thedescription. For example, in some embodiments, routine 700 can omit oneof blocks 706 or 708. In certain embodiments, blocks 704-708 can beperformed iteratively, e.g., on a data block by data block basis, orblocks 706 and 708 can be performed in parallel.

Reconstructing a Local Database Following a Failure

FIG. 8 is a flow diagram illustrative of an embodiment of a routineimplemented by an information management system for reconstructing alocal database 202, such as in the event of a failure associated withthe secondary storage computing device 106 hosting the local database202. Such failures can include hardware failures as well as softwarefailures such as a failure of a media agent 144 or other softwarecomponent executing on the secondary storage computing device 106. Oneskilled in the relevant art will appreciate that the elements outlinedfor routine 800 can be implemented by one or more computingdevices/components that are associated with the information managementsystem 100, such as the client computing device 102, data agent(s) 142,media agent(s) 144, secondary storage computing device 106,deduplication database 206, and/or storage manager 150. For instance,the routine 800 can be implemented by the information management system100 shown in any of FIGS. 2, 4, and 6. Accordingly, routine 800 has beenlogically associated as being generally performed by informationmanagement system 100. However, the following illustrative embodimentshould not be construed as limiting.

At block 802, the information management system 100 receives aninstruction to reconstruct one or more local databases 202, based atleast in part on a failure of the secondary storage computing device106. For example, in some embodiments, the information management system100 (e.g., the storage manager 140) can detect a failure (e.g., hardwareor software failure) of the secondary storage computing device 106.Following the failure, and as part of restoring the secondary storagecomputing device 106, the information management system 100 (e.g., themedia agent 144 or the secondary storage computing device 106) canreceive an instruction to reconstruct the contents of any localdatabases (e.g., 202A, 202B) that were lost as a result of the failure(e.g., contents of the local databases 202 that were not merged with thededuplication database 206 prior to the failure). For example, in someembodiments, the information management system 100 can identify thelocal databases 202 that were lost by accessing and reviewing entries inthe event log 204, which can be stored in persistent, non-volatilememory such as on one or more hard drives or solid-state drives, forexample. For instance, in the case of a failure of the media agent 144running on the secondary storage computing device 106, once the mediaagent 144 is re-started, the media agent 144 can identify localdatabases that should be reconstructed by accessing and reviewingentries in the event log 204. As another example, where there is ahardware failure associated with the secondary storage computing device106, a replacement secondary storage computing device 106 can be broughtonline, and the media agent 144 associated with the replacementsecondary storage computing device can similarly identify the localdatabases 202 that need to be reconstructed by accessing and reviewingentries in the event log 204.

At block 804, the information management system 100 can reconstruct thelocal databases 202 that were lost. In some embodiments, the informationmanagement system 100 can use the event log 204 to reconstruct the localdatabases 202. As described previously, the event log 204 can log eachstorage event. These events can include any events resulting inmodifications to the local databases 202 (e.g., resulting in creationand modification of working copies of entries from the deduplicationdatabase 206), or the actual modifications to the local databases 202themselves. In some embodiments, a new event log is created each time alocal database 202 is merged with the deduplication database 206. Insome cases, the event log 204 can include entries indicating when thelocal databases 202 were merged with the deduplication database 206.

Accordingly, in certain embodiments, the information management system100 can review the event log 204 to identify the most recent merge timeof the local database 202 with the deduplication database 206. Onceidentified, the information management system 100 can re-play thecontents of the event log 204 subsequent to the last merge toreconstruct the local databases 202. Where a new event log 204 iscreated after each merge, the information management system 100 canre-play all the contents of the event log 204 to reconstruct the localdatabases 202.

At block 806, the information management system 100 can merge thereconstructed local database(s) 202 with the deduplication database 206.The reconstructed local database(s) 202 can be merged with thededuplication database 206 as described above with reference to block510 of FIG. 5.

Additional, fewer, or different blocks can be used to implement theroutine 800 without departing from the spirit and scope of thedescription. For example, the routine 800 can include recordingdeduplication-related events in the event log 204, recording a createtime of a local database, which can be used to identify which localdatabases 202 were lost, and/or recording a merge time of a localdatabase with the deduplication database 206, etc. Furthermore, in someembodiments, once the information management system 100 detects asecondary storage computing device 106 failure, it can place thededuplication database 206 in an offline, or read-only state. In theoffline/read-only state, the deduplication database 206 can beinaccessible for writes and/or can be accessible only to anadministrator. Once the reconstructed databases 202 are merged with thededuplication database 206, the information management system 100 canreturn the deduplication database 206 to an online or read-write state.

Pruning of the Deduplicated Data Store Following a Failure

As indicated previously, in some embodiments the event log 204 is notconfigured to track pruning events, such as events that result in thescheduled deletion of a data block from the set of data blocks 207 or ofa corresponding database entry from the deduplication database 206.Thus, the reconstruction and merge process of FIG. 8 utilizing the eventlog 204 may in such cases result in only a partial recovery from thefailure associated with the secondary storage computing device 106because pruning events captured by the local database 202 prior to thecrash will be lost. The pruning events can be reissued in such cases aswill be described with respect to FIG. 9. In other embodiments, theevent log 204 captures pruning events, and a full recovery can beachieved using the event log 204, without reissuance of the pruningevents.

FIG. 9 is a flow diagram illustrative of an embodiment of a routineimplemented by an information management system for reissuing previouslyissued but unexecuted pruning events. At block 902 the informationmanagement system 100 can identify one or more data blocks and/orcorresponding database entries that were previously scheduled fordeletion, but have not yet been deleted, e.g., due to a failureassociated with the secondary storage computing device 106 in whichpruning information in the local database 202 was lost.

In some embodiments, the storage manager 140 can track which data blocksand/or corresponding database entries are to be pruned and/or whetherthey have actually been pruned successfully. For example, following apruning operation, the secondary storage computing device 106 cantransmit a report or other message to the storage manager 140 indicatingthat the secondary storage computing device 106 has completed thepruning. In some embodiments, the secondary storage computing device 106can individually identify the data blocks that have been pruned.Accordingly, in some embodiments, if the storage manager 140 does notreceive the message that the pruning has completed successfully, or ifit receives an indication that some but not all of the data blocksand/or corresponding database entries that should have been deleted haveactually been deleted, it can identify the data blocks and/orcorresponding database entries that still need to be deleted.

At block 906, the information management system 100 can instruct thededuplication database 206 to prune the identified one or more datablocks and/or corresponding database entries. Accordingly, the datablocks and/or corresponding database entries that were intended fordeletion can be pruned based on the new instruction. The informationmanagement system 100 can then initiate the pruning in any of themanners described herein, e.g., with reference to FIGS. 2 and 4-7.

Additional, fewer, or different blocks can be used to implement theroutine 900 without departing from the spirit and scope of thedescription. For example, in some embodiments, the routine 900 can omitblock 902. In such embodiments, the information management system 100can identify one or more data blocks that were to be pruned, but havenot been, and then instruct the deduplication database 206 to prune theidentified data blocks.

Terminology

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, refer tothis application as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively. The word “or” in reference to alist of two or more items, covers all of the following interpretationsof the word: any one of the items in the list, all of the items in thelist, and any combination of the items in the list. Likewise the term“and/or” in reference to a list of two or more items, covers all of thefollowing interpretations of the word: any one of the items in the list,all of the items in the list, and any combination of the items in thelist.

Depending on the embodiment, certain operations, acts, events, orfunctions of any of the algorithms described herein can be performed ina different sequence, can be added, merged, or left out altogether(e.g., not all are necessary for the practice of the algorithms).Moreover, in certain embodiments, operations, acts, functions, or eventscan be performed concurrently, e.g., through multi-threaded processing,interrupt processing, or multiple processors or processor cores or onother parallel architectures, rather than sequentially.

Systems and modules described herein may comprise software, firmware,hardware, or any combination(s) of software, firmware, or hardwaresuitable for the purposes described herein. Software and other modulesmay reside and execute on servers, workstations, personal computers,computerized tablets, PDAs, and other computing devices suitable for thepurposes described herein. Software and other modules may be accessiblevia local memory, via a network, via a browser, or via other meanssuitable for the purposes described herein. Data structures describedherein may comprise computer files, variables, programming arrays,programming structures, or any electronic information storage schemes ormethods, or any combinations thereof, suitable for the purposesdescribed herein. User interface elements described herein may compriseelements from graphical user interfaces, interactive voice response,command line interfaces, and other suitable interfaces.

Further, the processing of the various components of the illustratedsystems can be distributed across multiple machines, networks, and othercomputing resources. In addition, two or more components of a system canbe combined into fewer components. Various components of the illustratedsystems can be implemented in one or more virtual machines, rather thanin dedicated computer hardware systems and/or computing devices.Likewise, the data repositories shown can represent physical and/orlogical data storage, including, for example, storage area networks orother distributed storage systems. Moreover, in some embodiments theconnections between the components shown represent possible paths ofdata flow, rather than actual connections between hardware. While someexamples of possible connections are shown, any of the subset of thecomponents shown can communicate with any other subset of components invarious implementations.

Embodiments are also described above with reference to flow chartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products. Each block of the flow chart illustrationsand/or block diagrams, and combinations of blocks in the flow chartillustrations and/or block diagrams, may be implemented by computerprogram instructions. Such instructions may be provided to a processorof a general purpose computer, special purpose computer,specially-equipped computer (e.g., comprising a high-performancedatabase server, a graphics subsystem, etc.) or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor(s) of the computer or other programmabledata processing apparatus, create means for implementing the actsspecified in the flow chart and/or block diagram block or blocks.

These computer program instructions may also be stored in anon-transitory computer-readable memory that can direct a computer orother programmable data processing apparatus to operate in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the acts specified in the flow chart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computing device or other programmable data processingapparatus to cause a series of operations to be performed on thecomputing device or other programmable apparatus to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide steps for implementingthe acts specified in the flow chart and/or block diagram block orblocks.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further implementations of theinvention.

These and other changes can be made to the invention in light of theabove Detailed Description. While the above description describescertain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention under theclaims.

To reduce the number of claims, certain aspects of the invention arepresented below in certain claim forms, but the applicant contemplatesthe various aspects of the invention in any number of claim forms. Forexample, while only one aspect of the invention is recited as ameans-plus-function claim under 35 U.S.C sec. 112(f) (AIA), otheraspects may likewise be embodied as a means-plus-function claim, or inother forms, such as being embodied in a computer-readable medium. Anyclaims intended to be treated under 35 U.S.C. §112(f) will begin withthe words “means for”, but use of the term “for” in any other context isnot intended to invoke treatment under 35 U.S.C. §112(f). Accordingly,the applicant reserves the right to pursue additional claims afterfiling this application, in either this application or in a continuingapplication.

What is claimed:
 1. A method for removing information from adeduplication data store maintained in a secondary storage subsystem,the method comprising: identifying a first data block for removal from adata store of a secondary storage subsystem, the data store containing aset of data blocks including the first data block and corresponding to aset of files formed from the set of data blocks and stored indeduplicated fashion, the data store further including a set of datablock entries, each entry in the set of data block entries correspondingto a respective data block in the set of data blocks and comprising atleast a deduplication signature corresponding to the respective datablock and a reference count corresponding to the number of instances ofthe respective data block included in the set of files; generating amodified version of a working copy of a first data block entry of theset of data block entries, the first data block entry associated withthe first data block, the working copy being separate from the datastore and residing in a local data store in memory local to thesecondary storage computing device; updating the data store based on themodified version of the working copy to include information sufficientto indicate that the first data block should be removed from the datastore; subsequent to said updating, querying the data store to identifya group of one or more data blocks in the set of data blocks that shouldbe removed from the data store, the group including the first datablock; and removing the group of one or more data blocks from the datastore.
 2. The method of claim 1, wherein said updating comprisesupdating the value of the reference count of the working copy of thefirst data block entry to generate a modified reference count value. 3.The method of claim 2, wherein said querying comprises identifying thefirst data block for removal from the data store based on the modifiedreference count value indicating that the number of instances of thefirst data block is below a threshold value.
 4. The method of claim 3,wherein the threshold value is one and said updating comprisesdecrementing the reference count of the first data block entry from oneto zero.
 5. The method of claim 1, wherein said updating comprisessetting a flag of the working copy of the first data block entry.
 6. Themethod of claim 1, wherein said updating is initiated based on adetection of at least one: of expiration of a time threshold since aprevious update to the data store based on the contents of the localdata store; and a size threshold of the local data store being exceeded.7. The method of claim 1, wherein said updating comprises merging themodified version of the working copy with the first data block entrycontained in the data store.
 8. The method of claim 1, wherein the localdata store includes a plurality of working copies including the workingcopy corresponding to the first data block entry and a plurality ofadditional working copies corresponding to additional data block entriesin the set of data block entries, and wherein said updating comprisesmerging the plurality of working copies with the corresponding pluralityof data block entries in the set of data block entries.
 9. The method ofclaim 1, wherein said removing the group of one or more data blocks fromthe data store comprises, for at least one data block of the data blocksin the group, removing a copy of the data block from the data store andadditionally removing one or more pointers to the copy of the data blockfrom the data store.
 10. The method of claim 1, further comprising,subsequent to said querying, removing at least a portion the first datablock entry from the data store.
 11. A system for pruning adeduplication database, comprising: a data store contained in one ormore storage devices of a secondary storage subsystem, the data storeincluding a set of data blocks corresponding to a set of files formedfrom the set of data blocks, the set of files stored in deduplicatedfashion, the data store further including a set of data block entries,each entry in the set of data block entries corresponding to arespective data block in the set of data blocks and comprising at leasta deduplication signature corresponding to the respective data block anda reference count corresponding to the number of instances of therespective data block included in the set of files; and a secondarystorage computing device residing in the secondary storage subsystem andcomprising a local data store that is separate from the deduplicateddata store and resides in memory local to the secondary storagecomputing device, the secondary storage computing device furthercomprising computer hardware configured to: identify a first data blockfor removal from the data store; generate a modified version of aworking copy contained in the local data store that corresponds to afirst data block entry of the set of data block entries, the first datablock entry associated with the first data block; update the data storebased on the modified version of the working copy to include informationsufficient to indicate that the first data block should be removed fromthe data store; query the data store to identify a group of one or moredata blocks in the set of data blocks that should be removed from thedata store, the group including the first data block; and remove thegroup of one or more data blocks from the data store.
 12. The system ofclaim 11, wherein the secondary storage computing device is configuredto modify the value of the reference count of the working copy of thefirst data block entry to generate a modified reference count value. 13.The system of claim 12, wherein the secondary storage computing deviceis configured to identify the first data block for removal from the datastore based on the modified reference count value indicating that thenumber of instances of the first data block is below a threshold value.14. The system of claim 13, wherein the threshold value is one.
 15. Thesystem of claim 11, wherein the secondary storage computing device isconfigured to set a flag of the working copy of the first data blockentry as part of the modification of the working copy.
 16. The system ofclaim 11, wherein the update of the data store is initiated based ondetection of at least one of: expiration of a time threshold since aprevious update of the data store; and a size threshold of the localdata store being exceeded.
 17. The system of claim 11, wherein thesecondary storage computing device is configured to merge the contentsof the working copy of the first data block entry with the first datablock entry contained in the data store to perform the update of thedata store.
 18. The system of claim 11, wherein said local data storeincludes a plurality of working copies including the working copycorresponding to the first data block entry and a plurality ofadditional working copies corresponding to additional data block entriesin the set of data block entries, and wherein the secondary storagecomputing device is configured to update each of the plurality ofworking copies during the update.
 19. The system of claim 11, whereinfor at least one data block of the data blocks in the group, thesecondary storage computing device is configured to remove a copy of thedata block from the data store and additionally remove one or morepointers to the copy of the data block.
 20. The system of claim 11,wherein the secondary storage computing device is further configured,subsequent to said querying, to remove at least a portion the firstdatabase entry from the data store.